How to calculate the number of colors in the image palette. Tasks for calculating the information volume of a raster graphic image. Processing inside the chamber
Choosing flowers, every person thinks about how many colors should be in a bouquet. After all, in addition to the type and shade of plants, the bouquet plays a big role and their number. With the help of special developments, scientists managed to find out that already in 5-6 centuries BC, a certain numerical symbolism was observed. This fact suggests that the numbers have a long-proven value, so it is necessary to approach the number of colors for a gift.
Even and odd numbers
According to the ancient Slavic tradition, a motor number of colors in a bouquet has the meaning of mourning and charges a bouquet of negative energy.
That is why the pair quantity is brought to the funeral, to the graves or monuments. But the inhabitants of Eastern, European countries and the United States exists a completely different point of view about this. You have a clear number - the symbol of luck, happiness and love.
The happiest number in the bouquet of Germans is considered eight, despite the fact that it is even.
In the US, it is most often given to each other with 12 colors together. The inhabitants of Tokyo will calmly take place if they give them 2 flower, the main thing is that not 4 - this figure is considered to be a symbol of death.
Japanese, in general, there is their own language of plants, and each of their number has its own value. For example, one rose is a sign of attention, three - respect, five - love, seven - passion and adoration, nine - worship. A bouquet of 9 Floweries The Japanese will be presented with their idols, and out of 7 - beloved women. In our country, you can also give a clear number of plants if there are more than 15 pieces in one set.
Flower language
Few people know that the language of colors defines the number of buds in the bouquet. This language you need to know and consider who makes a gift to not regret your actions in the future. Suddenly for the recipient matters the number of colors in a bouquet.
What are the numbers say
Exception from the rule that prohibits presented a clear number of flowers - these are roses, there can be even two.
There is a separate language of these beautiful plants that determines the value for each number of them:
How to give a rose girl
Of course, every woman dreams at least once in life get from his beloved large number of roses, which will even be difficult to count.
But not always the composition of hundreds of elite plants is greater in terms of love for its chosen, than one beautiful red rose, especially if you teach it right.
It is not necessary to boil the flower into the wrapper, as well as add extra branches and plants to it, it will only reduce it.
A rose decorated with a velvet or satin ribbon will look much better. Sometimes you can pack it into a transparent wrapper, but only without excess shine. The same can be said about the bouquet of three buds. If included more than 7 flower, then they must be made in the package and tie ribbons to make a bouquet beautiful view And did not crumble.
Solving coding tasks graphic information.
Raster graphics.
Vector graphics.
Introduction
This electronic manual contains a group of tasks on the topic "Coding of graphic information". Collection of tasks is divided into tasks based on the specified theme. Each type of tasks is considered taking into account the differentiated approach, i.e., the minimum level tasks are considered (rating "3"), a common level (estimate "4"), advanced level (rating "5"). These tasks are taken from various textbooks (the list is attached). Solutions of all tasks are considered in detail, guidelines are given for each type of tasks, a short theoretical material is given. For ease of use, the manual contains links to bookmarks.
Raster graphics.
Type Types:
1. Finding the volume of video memory.
2. Determining the resolution screen and install graphic mode.
3.
1. Finding volume of video memory
The tasks of this type uses concepts:
· volume of video memory
· graphic mode
· color depth,
· screen resolution
· palette.
All such tasks you need to find one or another value.
Video memory -this is special rAMin which a graphic image is formed. In other words, it should be stored somewhere on the screen of the monitor. For this, there is a video memory. Most often its value from 512 KB to 4 MB for the best PCs during the implementation of 16.7 million colors.
Volume of video memory Calculated by the formula: V \u003d.I *X *Y, whereI. - color depth of a separate point, XY -the dimensions of the screen horizontally and vertically (the product X on y is the resolution ability of the screen).
The display screen can operate in two main modes: text team and graphic.
IN graphic mode The screen is divided into separate glowing points, the number of which depends on the type of display, for example 640 horizontally and 480 vertically. Glowing points on the screen are usually called pixelsTheir color and brightness can change. It is in the graphic mode that all complex graphic images created on the computer screen appear on the computer screen. special programsthat control the parameters of each screen pixel. Graphic modes are characterized by such indicators as:
- resolution (The number of points by which the image is played on the screen) - Typical current resolution levels 800 * 600 points or 1024 * 768 points. However, for monitors with big diagonal Permission can be used 1152 * 864 points.
- color depth(The number of bits used to encode color color), for example, 8, 16, 24, 32 bits. Each color can be viewed as a possible point point, then the number of colors displayed on the monitor screen can be calculated by the formula K.=2 I. where K. - the number of colors I. - color depth or bit depth.
In addition to the knowledge listed above, the student must have an idea of \u200b\u200bthe palette:
- palette (The number of colors that are used to play the image), for example, 4 colors, 16 colors, 256 colors, 256 shades of gray, 216 colors in the mode called High Color or 224, 232 colors in True Color mode.
The student should also know the connections between units of information measurement, be able to translate out of small units into larger, Kabletes and MB, use the usual calculator and Wise Calculator.
Level "3"
1. Determine the required volume of video memory for different graphic modes of the monitor screen, if color depth is known for one point. (2.76)
Screen mode | Color depth (bit to point) |
||||
Decision:
1. Total points on the screen (resolution): 640 * 480 \u003d 307200
2. Required volume of video memory V \u003d 4 bits * 307200 \u003d 1228800 bits \u003d 153600 byte \u003d 150 KB.
3. Similarly, the required amount of video memory for other graphic modes is calculated. When calculating the student uses a calculator to save time.
Answer:
Screen mode | Color depth (bit to point) |
||||
150 KB | 300 KB | 600 KB | 900 KB | 1.2 MB |
|
234 KB | 469 KB | 938 KB | 1.4 MB | 1.8 MB. |
|
384 KB | 768 KB | 1.5 MB | 2.25 MB | ||
640 KB | 1.25 MB | 2.5 MB | 3.75 MB |
2. Black and white (without gray gradation) raster graphic image has a size 10 '10 Points. What amount of memory takes this image? (2.6 8 )
Decision:
1. Number of points -100
2. Since only 2 colors are black and white. then the color depth is \u003d 2)
3. The volume of video memory is 100 * 1 \u003d 100 bits
Similarly, the request is solved 2.69
3. Storage raster image 128 size x 128 pixels took 4 CB of memory. What is the maximum possible number of colors in the image palette. (EGE_2005, demo, level A). (See also task 2.73 )
Decision:
1. Determine the number of image points. 128 * 128 \u003d 16384 Points or pixels.
2. The amount of memory to image 4 KB will express in bits, since v \u003d i * x * y is calculated in bits. 4 kb \u003d 4 * 1024 \u003d 4 096 byte \u003d 4096 * 8 bits \u003d 32768 bits
3. Find the color depth I \u003d V / (x * y) \u003d 32768: 16384 \u003d 2
4. N \u003d 2i, where N is the number of colors in the palette. N \u003d 4.
Answer: 4.
4. How many bits of video memory takes information about one pixel on a b / b screen (without halftone)? ( C. 143, Example 1)
Decision:
If the image of the h / b without halftone, then only two colors are used - Half and white, i.e. K \u003d 2, 2i \u003d 2, i \u003d 1 bits per pixel.
Answer: 1 pixel
5. What volume of video memory is required to store four pages of the image if the bit depth is 24, and the resolution of the display is 800 x 600 pixels? (, №63)
Decision:
1. Find the volume of video memory for one page: 800 * 600 * 24 \u003d bits \u003d 1440000 byte \u003d 1406.25 kb ≈1, 37 MB
2. 1.37 * 4 \u003d 5.48 MB ≈5.5 MB for storage of 4 pages.
Answer: 5.5 MB
Level "4"
6. Consider the volume of video memory of the computer, which is necessary for implementing the graphic monitor mode High Color with a resolution of 1024 x 768 points and a palette of colors from 65536 colors. (2.48)
If the student remembers that High Color mode is 16 bits per point, then the amount of memory can be found by defining the number of points on the screen and multiplying the color depth, i.e. 16. Otherwise, the student may argue as follows:
Decision:
1. According to the formula K \u003d 2i, where K is the number of colors, I - the depth of the color will determine the depth of color. 2i \u003d 65536.
Color depth is: i \u003d log \u003d 16 bits (calculate using programsWiseCalculator)
2 .. The number of image points is: 1024'768 \u003d
3. The required volume of video memory is: 16 bits' \u003d 12 bits \u003d 1572864 byte \u003d 1536 kb \u003d 1.5 MB (»1.2 MB. Dan in the workshop Ugrinovich). We teach students, translating into other units, divide on 1024, and not 1000.
Answer: 1.5 MB
7. In the process of converting raster graphic image The number of colors decreased from 65536 to 16. How many times does the amount of memory occupied by them decrease? (2.70,)
Decision:
To encode 65536 different colors for each point, 16 bits are required. To cite 16 colors, you need only 4 bits. Consequently, the amount of memory occupied decreased at 16: 4 \u003d 4 times.
Answer: 4 times
8. Is it enough video memory with a volume of 256 KB to work a monitor in 640 mode '480 and a palette of 16 colors? (2.77)
Decision:
1. We learn the volume of video memory, which will be required to work the monitor in 640x480 mode and the palette in 16 colors. V \u003d i * x * y \u003d 640 * 480 * 4 (24 \u003d 16, color depth is 4),
V \u003d 1228800 bits \u003d 153600 byte \u003d 150 kb.
2. 150 < 256, значит памяти достаточно.
Answer: Enough
9. Specify the minimum amount of memory (in kilobytes), sufficient to store any raster image of 256 x 256 pixels, if it is known that the image is used in the palette of 216 colors. Do not store the palette itself.
1) 128
2) 512
3) 1024
4) 2048
(EGE_2005, level a)
Decision:
We find the minimum amount of memory required for storing one pixel. In the image, a palette is used 216 colors, therefore, one pixel can be compared with any of 216 possible color numbers in the palette. Therefore, the minimum amount of memory, for one pixel will be equal to log2 216 \u003d 16 bits. The minimum amount of memory, sufficient to store the entire image will be equal to 16 * 256 * 256 \u003d 24 * 28 * 28 \u003d 220 BIT \u003d 220: 23 \u003d 217 bytes \u003d 217: 210 \u003d 27 KB \u003d 128 KB, which corresponds to a paragraph number 1.
Answer: 1.
10. Graphic modes with color depths 8, 16. 24, 32 bits are used. Calculate the volume of the video memory required to implement the color of color depths at various resolution screen abilities.
Note: the task comes down to solve the problem number 1 (the level "3", but the student itself needs to recall the standard screen modes.
11. How many seconds will need a modem transmitting messages at a speed of 28800 bits to transmit a color raster image of 640 x 480 pixels, provided that the color of each pixel is encoded with three bytes? (EGE_2005, level B)
Decision:
1. Determine the scope of the image in the bits:
3 bytes \u003d 3 * 8 \u003d 24 bits,
V \u003d I * x * y \u003d 640 * 480 * 24 bits \u003d 7372800 bits
2. We find the number of seconds to transfer the image: 7372800: 28800 \u003d 256 seconds
Answer: 256.
12. How many seconds will be required to be a modem transmitting messages at a speed of 14400 bits / s to transmit a color raster image with a size of 800 x 600 pixels, provided that in the palette of 16 million colors? (EGE_2005, level B)
Decision:
For coding, 16 million colors requires 3 bytes or 24 bits (True Color graphic mode). The total number of pixels in the image 800 x 600 \u003d 480000. Since 1 pixel accounts for 3 bytes, then 480000 * 3 \u003d 1 440,000 bytes or bits account for 480000 pixels. : 14400 \u003d 800 seconds.
Answer: 800 seconds.
13. The modern monitor allows you to receive various colors on the screen. How many memory bits takes 1 pixel? ( , p.143, example 2)
Decision:
One pixel is encoded by a combination of two signs "0" and "1". It is necessary to learn the length of the pixel code.
2x \u003d, log2 \u003d 24 bits
Answer: 24.
14. What is the minimum memory (in bytes), sufficient for storing a black and white raster image with a 32 x 32 pixel size, if it is known that in the image it uses no more than 16 grades of gray. (EGE_2005, level A)
Decision:
1. The color depth is equal to 4, because 16 color gradations are used.
2. 32 * 32 * 4 \u003d 4096 Bit memory for storing black and white image
3. 4096: 8 \u003d 512 bytes.
Answer: 512 bytes
Level "5"
15. The monitor works with 16 color palette in 640 * 400 pixel mode. For image encoding, 1250 KB is required. How many vocabulary pages does it take? (Task 2, test I-6)
Decision:
1. T. K. Page -the video memory section that enlists the information about a single screen image on the screen on the screen, i.e., simultaneously multiple pages can be placed in the video memory, then it is necessary to divide the number of video memory for the entire image to the amount of memory to 1 page. TO-the list pages K \u003d.Vizob /V1 p
Visor \u003d 1250 kb by condition
1. To do this, we calculate the volume of video memory for one page of the image with 16 color palette and the resolution of 640 * 400.
V1 p \u003d 640 * 400 * 4, where 4 is the depth of color (24 \u003d 16)
V1 p \u003d 1024000 bits \u003d 128000 byte \u003d 125 kb
3. K \u003d 1250: 125 \u003d 10 pages
Answer: 10 pages
16. The video memory page is 16000 bytes. The display operates in 320 * 400 pixels mode. How many colors in the palette? (Task 3, test I-6)
Decision:
1. V \u003d I * X * Y - volume of one page, V \u003d 16000 byte \u003d 128000 bits by condition. We find the depth of color I.
I \u003d 128000 / (320 * 400) \u003d 1.
2. We will define how many colors in the palette. K. =2 I,where K. - the number of colors I. - Color depth . K \u003d 2.
Answer: 2 colors.
17. Scan color image of 10 size '10 cm. Resolution scanner 600 dPI and color depth 32 bits. What information volume will have a graphic file received. (2.44, similarly solved problem 2.81 )
Decision:
1. The resolution of the 600 DPI scanner (dot per inch - dots) means that 1 inch length scanner is able to distinguish 600 points. We translate the resolution of the scanner of the scanner from dots to the point per centimeter:
600 dpi: 2.54 "236 points / cm (1 inch \u003d 2.54 cm.)
2. Consequently, the size of the image at the points will be 2360'2360 points. (multiplied by 10 cm.)
3. The total number of image points is:
4. The information file is equal to:
32 bits' 5569600 \u003d bit »21 MB
Answer: 21 MB
18. The volume of video memory is 256 KB. The number of colors used -16. Calculate the options for the resolution of the display. Provided that the number of image pages can be 1, 2 or 4. (, No. 64, p. 146)
Decision:
1. If the number of pages is 1, then the formula v \u003d i * x * y can be expressed as
256 * 1024 * 8 bits \u003d x * y * 4 bits, (as 16 colors are used, the depth of color is 4 bits.)
i.e. 512 * 1024 \u003d x * y; 524288 \u003d x * y.
The ratio between the height and width of the screen for standard modes does not differ among themselves and are equal to 0.75. It means to find X and Y, it is necessary to solve the system of equations:
Express x \u003d 524288 / y, we substitute on the second equation, we obtain Y2 \u003d 524288 * 3/4 \u200b\u200b\u003d 393216. We find y≈630; X \u003d 524288 / 630≈830
630 x 830..
2. If the number of pages is 2, then one page of 256: 2 \u003d 128 KB, i.e.
128 * 1024 * 8 bits \u003d x * y * 4 bits, i.e. 256 * 1024 \u003d x * y; 262144 \u003d x * y.
We solve the system of equations:
X \u003d 262144 / y; Y2 \u003d 262144 * 3/4 \u200b\u200b\u003d 196608; Y \u003d 440, x \u003d 600
Permissive ability can be 600 x 440..
4. If the number of pages is 4, then 256: 4 \u003d 64; 64 * 1024 * 2 \u003d x * y; 131072 \u003d x * y; We solve the system and the size of the point point 0.28 mm. (2.49)
Decision:
https://pandia.ru/text/78/350/images/image005_115.gif "width \u003d" 180 "height \u003d" 96 src \u003d "\u003e
1. The task is reduced to finding the number of points in the width of the screen. Express size diagonal in centimeters. Considering that 1 inch \u003d 2.54 cm, we have: 2.54 cm 15 \u003d 38.1 cm.
2. Determine the ratio between the height and width of the ECRana for frequently occurring screen mode 1024x768 Points: 768: 1024 \u003d 0.75.
3. Determine screen width. Let the screen width equal L., and height h.,
h: L \u003d 0.75, then H \u003d 0.75L.
According to Pythagora theorem, we have:
L2 + (0,75L) 2 \u003d 38.12
1,5625 L2 \u003d 1451.61
L ≈ 30.5 cm.
4. The number of points across the screen width is:
305 mm: 0.28 mm \u003d 1089.
Consequently, the maximum possible resolution of the monitor screen is 1024x768.
Answer: 1024x768..
26. Determine the ratio between the height and width of the monitor screen for various graphic modes. Does this ratio differ for different modes? a) 640x480; b) 800x600; c) 1024x768; a) 1152x864; a) 1280x1024. Determine the maximum possible resolution of the screen for the monitor with a diagonal of 17 "and the screen size of 0.25 mm. (2.74 )
Decision:
1. We define the ratio between the height and width of the screen for the listed modes, they almost do not differ among themselves:
2. Express the size diagonal in centimeters:
2.54 cm 17 \u003d 43.18 cm.
3. Determine the width of the screen. Suppose that the screen width is equal to L, then the height is 0.75L (for the first four cases) and 0.8L for the latter case.
According to Pythagora theorem, we have:
Consequently, the maximum possible resolution of the monitor screen is. 1280x1024
Answer: 1280x1024
3. Color and image encoding.
Students use the knowledge gained earlier system, the translation of numbers from one system to another.
The theoretical material of the topic is used:
The colored raster image is formed in accordance with the RGB color model, in which three basic colors are Red (red), Green (green) and Blue (blue). The intensity of each color is set to an 8-bit binary code, which is often expressed in a hexadecimal number system for convenience. In this case, the next RRGGBB recording format is used.
Level "3"
27. Record the red code in a binary, hexadecimal and decimal representation. (2.51)
Decision:
The red color corresponds to the maximum value of the intensity of the red color and the minimum values \u200b\u200bof the intensities of green and blue basic colors. , what complies with the following data:
Codes / colors | Red | Green | Blue |
binary | |||
hexadecimal | |||
decimal |
28. How many colors will be used if 2 level gradation levels are taken for each pixel color? 64 brightness level of each color?
Decision:
1. In total, each pixel uses a set of three colors (red, green, blue) with its brightness levels (0-lit, 1-not lit). So, k \u003d 23 \u003d 8 colors.
Answer: 8; 262 144 colors.
Level "4"
29. Fill out a table of colors at a 24-bit color depth in a 16-finished representation.
Decision:
At a color depth of 24 bits per each of the colors, 8 bits stand out, that is, 256 levels of intensity (28 \u003d 256) are possible for each of the colors. These levels are defined by binary codes (minimum intensity, maximum intensity). In binary representation it turns out the following formation of colors:
Title color | Intensity |
||
Red | Green | Blue |
|
The black | |||
Red | |||
Green | |||
Blue | |||
White |
Transferring to a 16-round number system we have:
Title color | Intensity |
||
Red | Green | Blue |
|
The black | |||
Red | |||
Green | |||
Blue | |||
White |
30.An the "small monitor" with a raster grid of 10 x 10 sizes there is a black and white image of the letter "K". To present the contents of the video memory as a bit matrix, in which the strings and columns correspond to the rows and columns of the raster mesh. ( , C.143, Example 4)
| |||||||||
Decision:
To encode the image on this screen, 100 bits are required (1 bits per pixel) of video memory. Let "1" mean a painted pixel, and "0" - not sharpened. The matrix will look like this:
0001 0001 00
0001 001 000
0001 01 0000
00011 00000
0001 01 0000
0001 001 000
0001 0001 00
Experiments:
1. Search for pixels on the monitor.
Arming a magnifying glass and try to see the triads of red, green and blue (RGB is the English. "Red -Green -Blue »Points on the monitor screen. (, .)
As the original source warns us, the results of experiments will be successful not always. The reason is. What is existed different technologies Making electron-ray tubes. If the tube is performed using technology "Shadow Mask", Then you can see a real mosaic from the points. In other cases, when instead of a mask with holes, a system of threads from the phosphor of three main colors is used (aperture lattice) The picture will be completely different. The newspaper cites very visual photos of three typical paintings that can see "curious students".
The guys would be useful to report that it is desirable to distinguish between the concepts of the "point point" and pixels. The concept of "point of screen" - Physically real objects. Pixels Logic image elements. How can this be explained? Recall. That there are several typical configurations of the picture on the monitor screen: 640 x 480, 600 x 800 pixels and others. But on the same monitor you can install any of them .. This means that pixels are not a monitor point. And each of them can be formed by several neighboring glowing points (in the limit of one). On the team to paint in blue color one or another pixel, computer, given mounted mode Display will paint one or several neighboring monitor points. Pixel density is measured as the number of pixels per unit length. The most common units called briefly as (DOTS PER INCH - the number of points per inch, 1 inch \u003d 2, 54 cm). DPI unit generally accepted in computer graphics and publishing. Usually the pixel density for the on-screen image is 72 dpi or 96dpi.
2. Spend an experiment B. graphic editor In case, for each color of the pixel, 2 gradation levels are taken? What colors do you get? Subscribe in the form of a table.
Decision:
Red | Green | Blue | Color |
Turquoise |
|||
Crimson |
Vector graphics:
1. Tasks on video coding.
2. Get the vector image using vector commands
With a vector approach, the image is seen as a description of graphic primitives, direct, arcs, ellipses, rectangles, circles, clasp, etc., the position and form of these primitives are described in the graphics coordinate system.
Thus, the vector image is encoded by vector commands, because E is described using an algorithm. Cut the straight line is determined by the coordinates of its ends, circle -center and radius coordinates polygon- coordinates of his corners, Tasted area- Line border and collar color. It is advisable that students have a table of system graphics system table (, p.150):
Team | Act |
Line to x1, y1 | Draw a line from the current position to the position (x1, y1). |
Line x1, y1, x2, y2 | Draw a line with the coordinates of the beginning x1, y1 and the coordinates of the end x2, y2. The current position is not installed. |
Circle X, Y, R | Draw a circle; X, Y - center coordinates, and R - radius length. |
Ellipse x1, y1, x2, y2 | Draw an ellipse limited by a rectangle; (X1, y1) -Cordinates of the left upper, A (x2, y2) - the right lower corner of the rectangle. |
Rectangle x1, y1, x2, y2 | Draw a rectangle; (X1, y1) - the coordinates of the left upper angle, (x2, y2) are the coordinates of the right-lower corner of the rectangle. |
Color drawing color | Set the current drawing color. |
Torm color color | Set the current color |
Paint x, y, border color | Paint arbitrary closed figure; X, y - coordinates of any point inside a closed figure, the color of the boundary line is a boundary line. |
1. Tasks on video coding.
Level "3"
1. Describe the letter "to" the sequence of vector commands.
Literature:
1., Informatics for lawyers and economists, p. 35-36 (theoretical material)
2., Informatics and IT, p.112-116.
3. N. Ugrinovich, L. Bosova, N. Mikhailova, Workshop on computer science and IT, P.69-73. (Tasks 2.67-2.81)
4., popular lectures on the computer device. - St. Petersburg., 2003, from 177-178.
5. In search of a pixel or types of electron-ray tubes. // Informatics. 2002, 347, p.16-17.
6. I. Semakin, E Henner, Informatics. Problem-workshop, T.1, Moscow, Lbz, 1999, p.142-155.
Electronic textbooks:
1., Information in the school course of informatics.
2., Reshebnik on the topic "Theory of Information"
Tests:
1. Test I-6 (coding and measurement of graphic information)
"Breakfast" is one of the parameters followed by all chasing, but few photographers really understand him. Photoshop offers 8, 16 and 32-bit file formats. Sometimes we see files marked as 24 and 48 bits. And our cameras often offer 12 and 14-bit files, although you can get 16 bits with a middle format camera. What does all this mean, and what really matters?
What is the bit depth?
Before comparing various options, let's first discuss what the name means. Bit is a computer unit of measurement relating to the storage of information in the form of 1 or 0. One bit can have only one of two values: 1 or 0, yes or not. If it were a pixel, it would be absolutely black or absolutely white. Not very helpful.
In order to describe a more complex color, we can combine several bits. Each time we add bits, the number of potential combinations is doubled. One bit has 2 possible values \u200b\u200b0 or 1. When combining 2 bits, you can have four possible values \u200b\u200b(00, 01, 10 and 11). When you combine 3 bits, you can have eight possible values \u200b\u200b(000, 001, 010, 011, 100, 101, 110, and 111). Etc. In general, the number possible options It will be the number of two erected into the degree of bits. Thus, "8-bit" \u003d 2 8 \u003d 256 possible integer values. In Photoshop, this is represented as integers 0-255 (internally, it binary code 00000000-11111111 for computer).
So the "bit depth" defines the slightest changes that you can do relative to a certain range of values. If our brightness scale from pure black to pure white has 4 values \u200b\u200bthat we get from a 2-bit color, then we will get the opportunity to use black, dark gray, light gray and white. It is quite small for the photo. But if we have a sufficient amount of bits, we have enough steps with a wide range of gray to create what we will see as a completely smooth gradient from black to white.
Below is an example of a comparison of a black and white gradient at different bit depths. This image is just an example. Click it to see the image in full resolution in JPEG2000 format with a bit of up to 14 bits. Depending on the quality of your monitor, you will probably see only the difference of up to 8 or 10 bits.
How to understand the bit depth?
It would be convenient if all the "bit depths" could be compared directly, but there are some differences in the terminology that you need to understand.
Please note that the image is above black and white. Color image, as a rule, consists of red, green and blue pixels to create a color. Each of these colors is processed by a computer and a monitor as a "channel". SoftwareFor example, Photoshop and Lightroom, consider the number of bits on the channel. Thus, 8 bits mean 8 bits per channel. This means that the 8-bit RGB snapshot in Photoshop will have a total of 24 bits on pixel (8 for red, 8 for green and 8 for blue). A 16-bit RGB image or LAB in Photoshop will have 48 bits per pixel, etc.
You could assume that 16-bit means a 16-bit on the channel in Photoshop, but in this case it works otherwise. Photoshop is actually used 16 bits per channel. Nevertheless, it refers to 16-bit pictures in a different way. He simply adds one bit to 15-bit. It is sometimes called 15 + 1 bits. This means that instead of 2 16 possible values \u200b\u200b(which equal to 65536 possible values) there are only 2 15 + 1 possible values, which is 32768 + 1 \u003d 32769.
Thus, in terms of quality, it would be fair to say that the 16-bit Adobe mode, actually contains only 15-bit. You do not believe? Look at the 16-bit scale for the info panel in Photoshop, which shows the scale of 0-32768 (which means 32769 values \u200b\u200bgiven zero. Why does Adobe do that? According to the Adobe Coke Developer application, this allows Photoshop to work much faster and provides an accurate midpoint for A range that is useful for mixing modes.
Most cameras will allow you to save files to 8-bit (JPG) or from 12 to 16 bits (RAW). So why does PhotoShop open 12 or a 14-bit RAW file as 12 or 14 bits? On the one hand, it would require a lot of resources for photosHop work and changing file formats to support other bit depths. And the opening of 12-bit files as a 16-bit is not in fact not different from the opening of the 8-bit JPG, and then conversion to 16 bits. There is no direct visual difference. But the most important thing, there are huge benefits of using file format with multiple additional bits (as we discuss later).
For displays, terminology changes. Manufacturers want the characteristics of their equipment to sound seductive. Therefore, the display modes 8-bit typically sign as "24-bit" (because you have 3 channels with 8-bit each). In other words, the "24-bit" ("True Color") is not very impressive for the monitor, it actually means the same as 8 bits for Photoshop. The best option It would be "30-48 bits" (the so-called "Deep Color"), which is 10-16 bits per channel, although for many more than 10 bits per channel is excesses.
How many bits can you see?
With a pure gradient (that is, the worst conditions), many can detect bands in a 9-bit gradient, which contains 2048 shades of gray on good display With support for a deeper color display. A 9-bit gradient is extremely weak, barely caught. If you did not know about his existence, you would not see him. And even when you look at him, it will not be easy to say where the boundaries of each color. A 8-bit gradient is relatively easy to see if you look at him intently, although you still be able to notice it, if you do not look after it. Thus, it can be said that a 10-bit gradient is visually identical to a 14-bit or deeper.
Note that if you want to create your own file in Photoshop, the gradient tool will create 8-bit gradients in the 8-bit document mode, but even if you convert the document to 16-bit mode, you will still have an 8-bit gradient. However, you can create a new gradient in 16-bit mode. However, it will be created in a 12-bit. The program does not have a 16-bit option for a gradient tool in Photoshop, but 12-bit is more than enough for any practical workSince it allows you to use 4096 values.
Do not forget to enable smoothing in the gradient panel, as it is best suited for testing.
It is also important to note that you are likely to face false "stripping" when viewing images at an increase in less than 67%.
Why use more bits than you can see?
Why do we have options, even more than a 10-bit in our chambers and Photoshop? If we have not edited photos, there would be no need to add more bits than the human eye can see. However, when we start editing photos, previously hidden differences can easily lick out.
If we are significantly lighted with shadows or dimly glare, we will increase some of the dynamic range. And then any shortcomings will become more obvious. In other words, the increase in contrast in the image works as a decrease in the bit depth. If we are enough to unscrew the parameters, in some parts of the picture may appear. It will show transitions between colors. Such moments usually become noticeable in the pure blue sky or in the shadows.
Why do 8-bit images look just like 16-bit?
When converting a 16-bit image to 8-bit, you will not see the differences. If so, then why use 16-bit?
It's all about the smooth editing. When working with curves or other tools you will get more steps to correct the tones and colors. Transitions will be smooth in 16 bits. Therefore, even if the difference cannot be initially noticeable, the transition to a smaller bit depth of color can be a serious problem later, when editing an image.
So how many bits really need in the chamber?
Changing 4 stops in will provide a loss of just over 4 bits. Changing 3 stops of the exposure is closer to loss of 2 bits. How often do you have to adjust the exposition so much? When working with the RAW, the correction to +/- 4 stops is an extreme and rare situation, but it happens, therefore it is desirable to have an additional 4-5 bits over the visible ranges to have a stock. With a normal range, 9-10 bits, with a margin of the norm can be about 14-15 bits.
In fact, you probably never need such a large amount of data for several reasons:
- There are not so many situations when you meet the perfect gradient. Clear blue sky is probably the most common example. All other situations have a large number of parts and flower transitions are not smooth, so you will not see the difference when using different bit depths.
- The accuracy of your camera is not as high to ensure the accuracy of color reproduction. In other words, there is noise in the image. Because of this noise, it is usually much more difficult to see the transitions between colors. It turns out that real images are usually not able to display color transitions in gradients, as the camera is not able to capture the perfect gradient that can be created programmatically.
- You can delete flower transitions during post-processing using the use of blur in Gauss and the addition of noise.
- Big stock of the bit is needed only for extreme tunnel amendments.
Taking all this into account, the 12-bit sounds like a very reasonable level of detail, which would allow to perform excellent post-processing. Nevertheless, the camera and human eye reacts in different ways. The human eye is more sensitive to the shade.
An interesting fact is that much depends on the program you are using for post-processing. For example, when drawing out the shadows from the same image in Capture One (CO) and in Lightroom, you can get different results. In practice it turned out that it spoils deep shadows with more than an analogue from Adobe. Thus, if you pull in LR, you can count on 5 stops, and in CO - only 4.
But still, it is better to avoid attempts to pull over 3 stops of the dynamic range due to noise and changes in the color shade. The 12-bit is definitely a reasonable choice. If you take care of quality, not the size of the file, then remove in a 14-bit mode if your camera allows.
How many bits should be used in photoshop?
Based on the above, it should be clear that 8-bit is not enough. You can immediately see the flower transitions in smooth gradients. And if you do not see it immediately, even modest adjustments can make this effect noticeable.
It is worth working at 16 bits even if your source file is 8-bit, for example, images in jpg. The 16-bit mode will give the best results, as it will allow minimizing transitions when editing.
There is no point in using a 32-bit mode if you do not handle the HDR file.
How many bits need for the Internet?
The advantages of 16 bits are to expand editing capabilities. Converting the final edited image of 8 bits is perfect for viewing pictures and has an advantage in creating small files for the Internet for more fast download. Make sure that smoothing in Photoshop is enabled. If you are using Lightroom to export into JPG, the smoothing is used automatically. It helps add a little noise, which must minimize the risk of noticeable color transitions in 8 bits.
How many bits need to be seal?
If you are typing at home, you can simply create a copy of the working 16-bit file and process it for printing, following the operating file. But what if you send your images over the Internet to the laboratory? Many will use 16-bit TIF files, and this is a great way. However, if you need a JPG for printing or you want to send a smaller file, you may encounter questions about the transition to 8-bit.
If your printing laboratory takes a 16-bit format (TIFF, PSD, JPEG2000), just ask specialists which files are preferred.
If you need to send JPG, it will be 8 bits, but it should not be a problem. In fact, the 8-bit excellent for final printing. Just export files from LightRoom with quality 90% and Adobe RGB color space. Make all the processing before converting the file in 8 bits and there will be no problems.
If you do not see the bands of the transition of colors on the monitor after converting to 8-bit, you can be sure that everything is in order to print.
What is the difference between the bit depth and color space?
The bit depth determines the number of possible values. The color space determines the maximum values \u200b\u200bor range (commonly known as "gamma"). If you need to use a box of color pencils as an example, a large bit depth will be expressed in more shades, and a larger range will be expressed as more rich colors regardless of the number of pencils.
To look at the difference, consider the following simplified visual example:
As you can see, increasing the bit depth. We reduce the risk of color transition bands. Expanding the color space (wider gamma) we will be able to use more extreme colors.
How does the color space affect the bit depth?
SRGB (left) and Adobe RGB (right) The color space (the range in which bits are applied), so a very large gamma theoretically can cause liabilities associated with color transitions if it is stretched too much. Remember that bits determine the number of transitions relative to the color range. Thus, the risk of obtaining visually noticeable transitions increases with the expansion of the gamma.
Recommended settings to avoid stripes
After all this discussion, it is possible to conclude in the form of recommendations that should be adhered to to avoid problems with the transitions of colors in gradients.
Camera settings:
- 14+ Bit RAW file is good choiceIf you want, the best quality, especially if you count on the adjustment of tone and brightness, for example, an increase in the brightness in the shadows of 3-4 stops.
- A 12-bit RAW file is perfectly suitable if you want to have a smaller use of files or disable faster. For the Nikon D850 camera, a 14-bit RAW file is about 30% more than a 12-bit, so it is an important factor. AND big files Can affect the ability to remove long frames of frames without overflowing the memory buffer.
- Never remove in JPG if you can. If you are shooting some events when you need to quickly transmit files and the quality of the pictures does not play a role, then of course JPEG will be an excellent option. You can also consider shooting in JPG + RAW mode if you need a better file subsequently. It is worth sticking to the SRGB color space if you are shooting in JPG. If you are shooting in RAW, you can ignore the settings of the color space. RAW files do not really have color space. It is not installed until the RAW file is convened to another format.
Lightroom and Photoshop (working files):
- Always keep working files into 16-bit. Use 8 bits for final exports in the JPG format for the Internet and print, if this format meets the requirements of printing equipment. This is normal to use 8-bit for final output, but this mode should be avoided during processing.
- Be sure to view the snapshot on a scale of 67% or more to make sure that there are no noticeable color transitions in gradients. In a smaller scale, Photoshop can create false stripes. This will be another our article.
- Be careful when using HSL in Lightroom and Adobe Camera Raw, since this tool can create colored stripes. It has very little common with bit depth, but problems are possible.
- If your source file is available only in 8-bit (for example, JPG), you must immediately convert it to 16 bits before editing. Subsequent edits on 8-bit images in 16-bit mode will not create too obvious problems.
- Do not use 32-bit space if you do not use it to combine multiple RAW files (HDR). There are some restrictions when working in a 32-bit space, and the files become twice as much. It is best to make HDR combining in Lightroom instead of using a 32-bit mode in Photoshop.
- HDR DNG Lightroom format is very convenient. It uses a 16-bit floating point mode in order to cover a wider dynamic range With the same bit. Having calculated that we usually need to correct the dynamic range in HDR only within 1-2 stops, this is an acceptable format that improves quality without creating huge files. Of course, do not forget to export this RAW in a 16-bit TIF / PSD when you need to continue editing in Photoshop.
- If you are one of the few people who need to use an 8-bit working mode for some reason, it is likely that the SRGB color space is probably the best.
- When using a gradient tool in Photoshop, noting the "Smoothing" option The program will use 1 additional bits. This can be useful when working in 8-bit files.
Export for the Internet:
- JPG with 8 bits and SRGB color space is ideal for the Internet. While some monitors are capable of displaying a large bit depth, an enlarged file size is probably not worth it. And while more and more and more monitors Support broader gammas, not all browsers properly support color management and can display the images incorrectly. And most of these new monitors probably never passed color calibration.
- The 8-bit is great for final printing, but use 16 bits if printing equipment supports it.
- The standard monitor is perfect for most tasks, but remember that you can see the color transition bands due to 8-bit displays. These bands may not really be in the pictures. They appear at the output stage on the monitor. On another display, the same snapshot may look better.
- If you can afford it, the 10-bit display is ideal for working with a photo. A wide range, such as Adobe RGB, is also perfect. But this is optional. You can create stunning pictures on the usual monitor.
A look into the future
IN this moment The choice of greater bit depths for you may not matter, since your monitor and printer can only work in 8 bits, but in the future everything can change. Your new monitor Will be able to display more colors, and printing can be carried out on professional equipment. Keep your working files into 16-bit. This will be enough to keep the best quality for the future. This will be enough to meet the requirements of all monitors and printers that will appear in the foreseeable future. This color range is enough to go beyond the range of human visa.
However, Gamma is another. Most likely, you have a SRGB color schema monitor. If it supports a wider spectrum of Adobe RGB or a gamut P3, then you better work with these gamma. Adobe RGB has an extended color range in blue, blue and green, and P3 offers wider colors in red, yellow and green. In addition to P3 monitors there are commercial printers that exceed the ADOBERGB gamma. SRGB and Adoberg is no longer able to cover the full range of colors that can be recreated on the monitor or printer. For this reason, it is worth using a wider range of color if you expect to print or view pictures on best printers And monitors later. For this, the Gamma Prophoto RGB will suit. And, as discussed above, the broader gamma needs a greater bit depth of 16-bit.
How to remove fullness
But if you encounter a longitudacy (most likely when switching to an 8-bit image, you can take the following steps to reduce this problem to a minimum:
- Convert a layer into a smart object.
- Add Blur in Gauss. Install the radius so as to hide the stripes. The radius equal to the width of the strip in pixels is ideal.
- Use the mask to apply blur only where it is necessary.
- And finally, add some noise. The graininess eliminates the look of smooth blur and takes a shot more holistic. If you are using Photoshop CC, use the Camera RAW filter to add noise.
in memory. Examination on the topic "Computer Graphics" 2 option 2Multimedia is a) obtaining moving images on the display; B) application program to create and process drawings; C) combining high-quality image with realistic sound; D) Informatics area, dealing with drawing problems on computer. 3 Select the correct sequence of the stages of the development of computer graphics: a) the appearance of graphic displays; b) symbolic graphics; c) the appearance of grapheatteners; d) the appearance of the printer of color printing. A) a, c, d, b; B) b, c, a, d; C) b, a, c, d; D) a, b, d, c. 3. The creation of arbitrary drawings, drawings is engaged in a) scientific graphics; B) design graphics; C) business graphics; D) illustrative graphics. 4. What computer device performs the sound sampling process? BUT) sound card; B) columns; C) headphones; D) processor. 5. The raster image is ... a) a mosaic of very small elements - pixels; B) a combination of primitives; C) Flower palette. 6. Point graphic Screen It can be painted in one of the colors: red, green, brown, black. What volume of video memory will be highlighted for encoding each pixel? A) 4 bits; B) 2 bytes; C) 4 bytes; D) 2 bits; E) 3 bits. 7. GR tool is: a) line; B) color; C) sprinkler; D) drawing. 8. Graphic primitive is: a) line; B) eraser; C) copying; D) color. 9. To obtain 4 color images to each pixel, it is necessary to highlight a) 1 byte; B) 1 bit; C) 2 bytes; D) 2 bits 10. Discrete signal is ... a) digital signal; B) the number of measurements produced by the device in 1 second; C) continuously changing with time the value of the physical quantity; D) Table with the results of measuring the physical size in fixed moments of time. 11. At what kind of sampling frequency, there is more accurate sound playback? A) 44.1 kHz; B) 11 kHz; C) 22 kHz; D) 8 kHz. 12. What can be attributed to disadvantages raster graphics compared to the vector? A) a large scope of graphic files. B) Photographic quality Images. C) the ability to view the image on the screen graphic Display. D) distortion when scaling. 13. What can be attributed to the disadvantages of the monitor? A) low weight; B) darkening when a change in the viewing angle; C) the absence of E / M of radiation; D) Small volume. 14The coding of a green color serves code 1011. How many colors in the palette? 15Nate the volume of the recorded audio quad file, if the record was written 4 minutes, using the 16-bit sound coding depth and the sampling rate of 32kc. 16The storage of a raster image of 64 sizes to 64 pixels took 512 memory bytes. What is the maximum possible number of colors in the image palette? 17 In the process of converting a raster graphic file, the number of colors decreased from 512 to 8. How many times did the information file decreased?
1) The volume of the audio stereoid file is 7500 KB, the depth of sound is 32 bits, the duration of the sound of this file is 10 seconds. With what frequency of samplingrecorded by this file?
2) Informational scope of the dimensions of 30x30 points is 1012.5 bytes. Determine the number of colors in the palette used for this image.
Between the number of colors defined by the point of the bitmap image, and the number of information that needs to be highlighted for storage, There is a dependence determined by the relation (formula R. Hartley):
Where
I.- the amount of information
N. – the number of colors setpoint.
So, if the number of colors defined for the image point, N \u003d256, then the amount of information necessary for its storage (color depth) in accordance with the formula R. Hartley will be equal I. \u003d 8 bits.
Computers for displaying graphic information use various graphic monitor operation modes. Here it should be noted that in addition to the graphical mode of operation of the monitor, there is also a text mode in which the monitor screen is conditionally divided into 25 rows of 80 characters in the row. These graphic modes are characterized by the resolution of the monitor screen and the quality of color reproduction (color depth).
To implement each of the graphic modes of the monitor screen, a certain information volume of video memory Computer (V), which is determined from the ratio
Where
TO - Number of image points on the monitor screen (K \u003d A · B)
BUT - Number of horizontal points on the monitor screen
IN - Number of vertical points on the monitor screen
I. - amount of information (color depth), i.e. The number of bits per 1 pixel.
So, if the monitor screen has a resolution of 1024 to 768 points and a palette consisting of 65536 colors, then
color depth will be I \u003d log 2 65 538 \u003d 16 bits,
the number of image points will be equal K \u003d 1024 x 768 \u003d 786432
The required information volume of the video memory will be equal to V \u003d 786432 · 16 bits \u003d 12582912 BIT \u003d 1572864 byte \u003d 1536 KB \u003d 1.5 MB.
Files created on the basis of raster graphics assume data storage of each individual image point. No complex mathematical calculations are required to display raster graphics, it is enough to obtain data about each image point (its coordinates and color) and display them on the computer monitor screen.