Complete self-study manual ps? Jiuzhang

9- 1 Use color sampler and information panel to identify colors.

A tool that can accurately identify colors: information panel

Execute the "Window-Info" command to open the panel, put the cursor on the color to be viewed, and the panel will display its color value.

How to accurately understand the change of color value?

1) Click the position to be observed with the color sampling tool to establish the sampling point, and the information panel displays the color value of the sampling position.

2) Two sets of numbers: the slash is preceded by the front value and followed by the back value.

3) Four sampling points: an image can have up to four sampling points. Click and drag the sampling point position, and the color value will change accordingly.

4) Delete the sampling point: Alt+ click the sampling point to delete it. Shift+Alt+ click the sampling point; If you want to delete all color sampling points, click the Clear button.

5) "sampling size": "sampling point"-point shadow; "3*3 average"-that is, take the average value within 3 pixels.

9-2 Information Panel

When there is no operation, information such as color value under the cursor, file status and current tool usage tips will be displayed. If an operation is performed, the panel will display information related to the current operation.

Window-Info Opens the information panel.

Display color information: the precise coordinate and color value of the cursor will be displayed, and an exclamation point will appear when it exceeds the CMYK color gamut.

Functions of information panel

Display Selection Size: Displays the width and height of the selection box.

Display the size of the bounding box: The width change, height and rotation angle of the bounding box will be displayed by using the cropping tool and the scaling tool.

Display the starting position and change the angle and distance: When moving the selection, use the line tool, pen tool and gradient tool to display the starting position, role and distance as the mouse moves.

Displays transformation parameters, such as scaling and rotation.

Display status information: display information such as document size, document configuration file, document size, scratch disk size, efficiency, time and current tool.

Displays a tooltip message: If enabled.

_ Click the pipette icon and mouse coordinates on the information panel to open the drop-down menu and change the reading options and units.

Set information panel options

You can open the InfoPanel Options dialog box by executing the Panel Options command in the InfoPanel menu.

First color information:

Color information displayed by the first straw; Actual color, showing the value in the current color mode. The values of proof color and output color. Grayscale, RGB and CMYK display the values in these modes. Total Ink Displays the total percentage of ink. Opacity Displays the opacity of the current layer.

Second color information: Set the color information displayed by the second straw in the panel.

Mouse Coordinate: Displays the cursor position measurement unit.

Status Information: the display content of "Status Information" in the display panel.

Show Tooltips: If this option is selected, you can display various tips of the currently used tools at the bottom of the panel.

9-3 Gamut and Overflow

The digital cameras, scanners, monitors, printers and printing equipment we use all have their own specific color spaces.

Color gamut: refers to the range of colors that a device can produce. Lab has the widest color gamut, followed by RGB and the smallest is CMYK.

Overflow: The color that the printer can't output accurately is called overflow.

How to check the overflow?

. Both Color Selector and Color will have warning messages and provide an alternative option.

. Check the overflow color: you can first establish sampling points in the image with a sampler, then right-click the pipette in the information panel and select CMYK, whether there is an exclamation point.

. Turn on overflow warning: You can execute the "Vision-Gamut Warning" command, and the area covered by gray in the figure is the overflow area. Once again, turn off the warning in Sewn.

. View overflow in the color selector: When the color selector is opened and the gamut warning command is executed, the overflow color in this dialog box will also be displayed in gray. Drag the slider up and down to see which color system loses the most color.

. Zero address instruction

Simulate printing on the video screen: When making printed matter, we can see what these images will look like when printed in the future on the computer. Methods: Open the file, execute the command of "View-Proofreading Settings-CMYK at Work", and then execute the command of "View-Proofreading Color" to start electronic proofing. ps will simulate the effect of the image on the commercial printing machine. To close it, please execute it again.

9-4 Histogram

Histogram is a graphic representation of pixels at each brightness level in an image, which shows the distribution of pixels in the image. By observing the histogram, we can judge whether the shadows, midtones and highlights of the photos have enough details, so as to make accurate adjustments.

Execute the "window-histogram" command to open the histogram panel.

Channel: In fact, there are not only channels, but also brightness and color. Select a channel and the panel will display the histogram of the channel. Select Brightness to display the brightness and intensity values of the composite channel. Select a color to display the composite histogram of each color channel in the color.

Refresh without cache: click this button to refresh the histogram and display the latest statistical results in the current state.

Cache Data Warning: Click Warning? Icon, you can refresh the histogram.

Change the display mode of the panel: By default, compact view is the simplest display mode. The extended view displays a histogram with statistics and controls. The All Channels view displays histograms with statistics and controls, and also displays a single histogram for each channel. Display Histogram in Primary Colors can also view color channels.

Two histograms: Two histograms will appear in the histogram panel when the image is adjusted with color scales and curves. Black is the histogram of the current state, and gray is the histogram before adjustment. After adjustment, the original histogram will be replaced by the new histogram.

Statistics in the histogram:

Average value: displays the average brightness value of pixels. By observing this value, the hue type of the image can be judged. The value is big and bright.

Standard deviation: shows the range of brightness values. The higher the value, the more drastic the image changes.

Median: Displays the median of the brightness value range. The brighter the hue of the image, the higher the value.

Pixels: The total number of pixels.

Color Scale/Quantity: Color Scale shows the brightness level of the area below the cursor; The number displays the total number of pixels corresponding to the brightness level below the cursor.

Percentage: displays the percentage of partial color scale sampling, and samples are taken in all color scale ranges. The value is 100%.

Cache Level: Displays the current image cache level used to create the histogram.

Judging the hue and exposure of photos from histogram

Exposure is one of the most important elements in photography. So how do you judge whether the exposure is correct? Answer, check the histogram. Similarly, when processing photos in ps, you can open the histogram panel and adjust the color tone and exposure of photos in a targeted manner.

How to read the histogram?

The left side of the histogram represents the shadow area of the image, the middle represents the middle area and the right side represents the highlight area. There are 256 shades from shadows (black, level 0) to highlights (white, level 255) * *.

The mountains in the histogram represent the data of the image, and the peaks represent the distribution of the data. A higher peak indicates that the region contains more pixels, while a lower peak indicates that the region contains fewer pixels.

Photos with accurate exposure: Photos with accurate exposure have even tones and rich light and dark levels, and the bright parts will not lose details, and the dark parts will not be dark. As can be seen from the histogram, the peak value is basically in the center, and there are pixels in each color scale (0-255) from left to right.

Underexposed photo: The picture is very dark. In its histogram, the peaks are distributed in the left toilet of the histogram, and there are no pixels in the middle and highlights.

Overexposed photos: the picture is bright in tone, and the highlight area of the person loses its hierarchy. On the histogram, the whole peak shifts to the right, and the shadow lacks pixels.

Photos with low contrast: The photos are gray, and there are gaps at both ends of the histogram, indicating that the shadow and highlight areas lack necessary pixels. The darkest tone in the image is not black, and the brightest tone is not white. The dark place is not dark, and the bright place is not bright, so the photo is gray.

Missing photos in the dark part: The dark part is dark, with no hierarchy, and no details can be seen. Some peaks in the histogram are close to the black part at the left end.

Photos with highlights overflowing: Some bright areas become completely white without any layers. Some peaks in the histogram are near the white part at the right end of the histogram (color code 255).

Attention? Observe the histogram, focusing on "Are there any dark parts missing?" "Is there any bright spot overflowing?"

9-5 color scale

Levels can adjust the intensity levels of shadows, midtones and highlights of an image. You can also correct the hue range and color balance, which means that the color scale can adjust not only the hue, but also the color.

Attention? When adjusting photos, it is best to open the histogram panel and observe the changes of the histogram.

Preset: the drop-down list is the preset scheme. From the menu button drop-down list on the right, you can choose the "Save" command to save as a preset file.

Channel: You can select a color channel and adjust it to change the color. You can hold down the shift key to select multiple channels.

Input Levels: The slider adjusts the shadows, midtones and highlights of the levels.

Black slider, shadow slider (level 0). Gray slider, middle slider (color scale 128). White slider, highlight slider (color scale 255). The color corresponding to each slider is on the output bar.

Output color scale: you can limit the brightness range of the image, thus reducing the contrast and making the image fade.

Set black field: click in the image with this tool to adjust the pixel of the clicked point to black, and all pixels darker than this point in the original image will become black.

Set Gray Point: Click a point in the image with this tool to determine it as a gray point, which is usually used to correct color cast.

Set white field: Click this point to make it white, which is whiter than all lit pixels.

Automatic: Apply automatic color correction.

Options: Opens the Automatic Campus Color Options dialog box to set the ratio of black and white rabbit pixels.

Tone mapping principle of color standard

Enter the color code, the shadow slider moves to the right, and all the moved positions are mapped to black. The highlight slider moves to the left, and all the moved positions are mapped to white. The middle slider can also be moved, but it will not significantly change the highlights and shadows.

Output color scale, two sliders are used to limit the brightness range of the image. When you move the "dark" slider to the right, all the moved areas are mapped to the point gray, and the darkest tone in the image is no longer dark. The white slider moves to the left, and the sliding range is mapped to the current light gray. Image? The brightest hue is no longer white, and the hue becomes dark.

Case, make the tone of the photo clear and bright.

1) Open an underexposed photo: the tone is dark and the color is not bright and yellow.

2) Open the "color scale" to observe the histogram, with the peak to the left. Drag the middle slider to the left, readjust the gray center, and make the tone brighter = show more details.

3) Open the saturation dialog box, and select the full image to improve the overall saturation of the color. Then select Red, Yellow and Green to adjust their saturation.

4) The color is bright, but there are some partial colors. Execute the "Image-Auto Tone" command to correct the color cast.

Case: Adjust the sharpness of photos in threshold mode.

Contrast: The closer the shadow and highlight sliders are to the middle, the stronger the contrast of the image and the more details are lost. If the sliders can be accurately positioned at the beginning and end of the histogram, the best contrast can be obtained without losing the details of the image.

1) opens a dialog box of materials and color codes, and observes the histogram. The two ends of the mountain range do not extend to the two endpoints, indicating that the darkest place is not black, the brightest place is not white, the contrast is not enough, and the tone is a little gray.

2) Hold down the Alt key and drag the shadow slider to the right to temporarily switch to the threshold mode, so that we can see a high-contrast preview.

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Case: Define photos with gray dots to correct color cast.

1) Open the photo and check the color cast: it is easier to determine the color cast in light or neutral image areas, such as white shirts and gray roads.

2) Use the color sampler to click Create Sampling Point in the white place, and an information panel will pop up to display the sampled color values. The same amount of red, green and blue in r181g187b202.ps produces gray. If the RGB value of the area that should be gray in the photo is different, it means that the color is cast. If r is higher than other values, the image is red; If the value of g is higher than other values, the image is green; If the b value is higher than the other two color values, it means blue. This box is blue.

3) Click the Levels button of the Adjustment panel to create a level adjustment layer. Select the gray field pipette, place the cursor on the selected sampling point, and then click. PS will calculate the RGB average of the click point, and adjust the average brightness of other midtones according to this value. , thus correcting the color cast. However, inaccurate sampling points will lead to new color cast.

9-6 curve

It has the functions of color scale, threshold and brightness/contrast, and can add 14 control points on the curve. Click the curve to add control points, drag the control points and change the shape of the curve to adjust the hue and color of the image. Click the control point to select it. Hold down the shift key and click to select multiple control points. Select a control point, and then press Delete to delete it.

Basic options for the curve command:

Channel: Select the color channel to adjust.

Preset: contains various preset adjustment files provided by ps, and the drop-down menu for storing and loading commands is on the right. Such as color negative, contrast, darker, increased contrast, brighter, linear contrast, medium contrast, negative and strong contrast.

Adjust the curve by adding points: press the state by default, click add new control point, and drag the control point to change the curve shape at will to adjust the image. In RGB mode, the curve bends upward, which can brighten the tone; The curve bends downward to darken the tone. In CMYK mode, the curve can be bent upward to darken the tone, and the curve can be bent downward to brighten the tone.

Drawing a curve with a pencil: hand-drawn effect

Smooth: After manual drawing, click this button to smooth the curve.

Image adjustment tool (finger painting): after selecting the I-hai tool, place the cursor somewhere in the image, and there is a small dot somewhere corresponding to the curve-representing the position of the curve corresponding to the cursor. Click and drag-add control points and adjust the hue in the picture.

Input/output: input, adjust the previous pixel value, output and display the adjusted pixel value.

Set black field/white field/gray point; Consistent with the color code.

Automatic: Automatic correction.

Option: Opens the Self-Calibration Pi Color dialog box.

Curve display options: More options for displaying curves.

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Tone and color matching principle of curve

Ctrl+M, open the curve dialog box. Horizontal gradient bar (input color scale): indicates the original intensity value of the pixel. Vertical Fading Color Band (input color scale): indicates the brightness value of the adjusted pixel.

Single arch curve: add control points and merge? Move, the image will be brighter, the middle click point (middle tone) will be the brightest, and the lower left (shadow) and upper right (highlight) will be a little brighter.

Single concave arch curve: opposite to the upper concave arch curve.

The positive S-shaped curve is concave on the left and convex on the right: the highlight area becomes brighter and the shadow area becomes darker, thus enhancing the contrast of hue.

The inverted S-shaped curve is convex on the left and concave on the right: the highlight area becomes dark and the shadow area becomes bright, thus reducing the contrast of hue.

The lower left control point (shadow) moves up: the image black is replaced by gray, that is, the shadow area becomes bright.

The upper right control point (highlight) moves down: the highlight turns gray. As a result, the highlighted area darkens.

The left and right endpoints move vertically towards each other: the color contrast becomes smaller and the color becomes gray. If it is a horizontal straight line, the color disappears and all pixels in the image turn gray. The higher the horizontal line, the brighter the gray scale.

Overflow of highlights; When the high light spot moves to the left, all the moved areas are converted into highlight colors, white, and the highlight areas lose details, that is, highlights overflow.

Shadow overflow: the control point at the end of the shadow moves to the right, and all the moved areas become shadow color and black, so the shadow area will lose details, that is, shadow overflow.

The ends of highlights and shadows move towards each other: similar to an S-shaped curve, but the midtones are compressed and the details are lost. When it moves to the middle vertical line, it can produce the effect of color separation.

Negative effect: the shadow and highlight are interchanged, which can reverse the image into a negative, just like executing the reverse command.

N-curve: some images can be reversed.

Similarities and differences between curves and color codes

There are two preset control points on the curve, among which "Shadow" can adjust the shadow area of the photo, which is equivalent to the shadow slider in the color scale. Highlight can adjust the highlight area of the photo, which is equivalent to the highlight slider in the color scale. If you click the middle tone in the center of the curve at 1/2, it is equivalent to the highlight slider in the color scale. The curve can have 16 control points, and the color code is only? A, so the curve adjustment is finer. It can adjust the pixels in a certain color range without affecting other pixels, which is impossible for the color scale. This is the power of curves.

How to move the control point slightly? Arrow keys on the keyboard. Usually, when we edit an image, we only need to adjust the curve slightly to achieve our goal. The larger the amplitude, the easier it is to destroy the image.

Case adjustment severely underexposed photos

1) Open the photo, the picture is very dark, and there are few details in the shadow area.

2)ctrl+J copies the photo as a layer 1/ mode as a color filter =, thus improving the overall brightness of the image.

3) Press ctrl+J again to copy the color filter layer.

4) Click the curve button in the adjustment panel to create a curve adjustment layer. Click to add a control point at the lower part of the curve, and drag the curve up to lighten the dark area.

5) Correct the color cast, create a "hue/saturation" adjustment layer, select "red" and drag the "lightness" slider to brighten the red color, which can reduce the saturation of the red color and make the character's skin white.

-[x] How to avoid new color cast during adjustment. Just set the blending mode of the adjustment layer to brightness.

9-7 channel color matching technology

Relationship between color matching command and channel: When we use any color matching command to adjust the color, we all influence the color through the channel.

Relationship between color channels and colors: in each color channel, gray represents the content of one color, bright areas represent a large number of corresponding colors, and dark areas represent less corresponding colors.

How to increase or decrease the color in a channel: just brighten or darken the corresponding channel. The dialog boxes Horizontal and Curve both contain channel options. We can select a channel and adjust its brightness, thus affecting the color. Brighten the red channel = add red; Bright green = increasing green; Brighten blue = increase blue. The brightness of a channel is closely related to the amount of color it contains, but this is only one aspect.

Color conversion relationship of color wheel:

In fact, colors can also influence each other, that is, if we increase the content of a color, we will reduce its complementary color content. On the contrary, reducing the content of a color will increase its complementary color content. In other words, channel color matching is like a seesaw, one side goes down, and the other side? Colors must appear. The color wheel and the color phase ring represent the complementary relationship of colors.

Attention? The commands "Color Balance" and "Change" are also adjusted based on the complementary relationship of colors.

situation

Use the passage to bring out the warm sunset glow.

1) Open a sunset in winter, with cool colors. Adjust its first warm tone with the channel to turn white snow into golden sand.

2) Create a curve adjustment layer and select the red channel-click Add Control Point on the curve, drag the curve upward to make the channel bright and add red.

3) Select the blue channel, drag the curve downward to darken the channel, reduce the blue, that is, increase its complementary color yellow, and the picture appears warm golden yellow.

4) Select RGB composite channel, adjust the curve to "S" shape, and increase the contrast. Pay attention to the sunshine when adjusting to avoid overexposure.

9-8Lab color matching technology

Lab mode is the color mode with the widest color gamut, including RGB/CMYK color gamut. Adjusting the channels of RGB and CMYK mode images will not only affect the color, but also change the brightness of the color. The laboratory is completely different. It can separate brightness information from color information, so we can adjust hue without changing color brightness. Many advanced technologies convert images into Lab mode, and then process the images to achieve the effect that RGB images can't achieve.

Channels in lab mode:

Conversion: "Image-Mode -Lab Color"

L- brightness channel, indicating the brightness of the image. The range is 0- 100, 0- black, 100- white.

A- stands for the spectral change of green-magenta. (+127 ~ _ 128} complementary color

B- stands for the spectral change from blue to yellow. Complementary colors.

Lab channel and color: the higher the channel, the warmer the color, the darker the channel and the colder the color. So if we brighten channel A, it will increase magenta (warm color); Dimming channel a will increase green (cool color); Brightening channel b will increase yellow; Dimming the B channel will increase the blue color.

-[x] The A and B channels of the black-and-white image are 50% gray. When the brightness of channels A and B is adjusted, the image will be converted to monochrome.