How to skillfully apply Photoshop Image Processing

How to skillfully apply Photoshop's image processing menu

before printing, when facing various originals sent by a large number of customers, we found that some must use Photoshop for color correction when the photo stretching curve reaches the peak E. Using Photoshop software can adjust the poor originals, which is the remedy taken when the customer's originals are of poor quality. Here, the software used by the author is Photoshop 7.0

color preset

it is important to understand the color preset in Photoshop software before processing image originals. Photoshop itself can carry out color management, and color presetting can be carried out in Photoshop. It is the color parameter of color space conversion, and its stability and unity are the basis for realizing soft proofing

1. RGB setting: the default value is "sRGB", which is suitable for image, screen display or page display, but not for color printing and publishing. "Color match RGB" or "Adobe RGB (1998)" can be used for printing and publishing. "Adobe RGB (1998)" setting is more suitable for prepress production. The screen contrast "gamma", whiteness "white point" and screen three primary colors change automatically with the RGB setting

2. CMYK setting: Photoshop's preset color separation conversion method (from RGB to CMYK) generally uses the default color separation table in Photoshop. After introducing digital proofing, our factory has established its own printing color management data for coated paper, offset paper and paper used in the back end of printing. When adjusting pictures, call different CMYK curves according to the paper used for back-end printing

3. Open document setting: This determines how Photoshop sets the color configuration. Especially when opening old documents, it is often found that it is necessary to understand the mechanical properties and destructive properties of materials when compressed through compression experiments. The description of old documents is different from that of Photoshop. The first option in this setting determines to still apply the color setting of old documents; The second option allows the old document to apply the current color settings; The third option indicates that color management is not applied

image adjustment

the color setting is clear, and the conversion selection for different situations is purposeful. Let's talk about the application of image adjustment in Photoshop, which can be roughly divided into the following steps

1. Establish the characteristic curve from white field to black field. According to the results of gray balance test in proofing and printing, it is required to be consistent with the gray balance curve in picture adjustment

2. Check the scanning error, select "image/adjustment/curve" (shortcut key ctrl+m) to verify whether the white field is balanced (white field gray balance C5, m3, Y3) and the black field is balanced (dark field gray balance c96, M88, y88, k85)

3. Check whether the picture is biased and whether the data from neutral white to neutral black is correct

4. Select "window/display channel", open the black version in the channel panel to make more plastic with good performance become the channel of packaging materials, analyze the gradient and data of the black version, and select "curve" and "hierarchy" under "image/adjustment" to adjust the gradient of the black version

the usage of the black version is like this. When the C, m, y tricolor version is mainly used in the traditional color separation, the black version is supplemented, and the black version uses short tone black to compensate for the lack of industrialization effect that the superposition of three colors cannot achieve pure black. The other uses GCR color separation, which is mainly black, supplemented by three colors. Equivalent black is used to replace the gray and the part close to gray composed of the superposition of C, m and Y colors from high light to dark tone, and the long tone black version is used to compensate for the ink volume of the black version

it should be emphasized here that the black version plays an extremely important role in the application of picture color. It is the support of the whole picture skeleton, level and spirit. If the black version is well handled, it can make the picture level clear, colorful and stereoscopic. If the black version is not handled properly, the picture will become dark and unclear, and the color level will not be reflected

usually, the original color matching is carried out after scanning, because it is not enough for some poor originals to only rely on the color matching during scanning. According to the actual situation, before adjusting the originals, it is necessary to classify all kinds of originals: reflection, transmission, material CD, uploading and downloading digital images; Skin color, scenery, metal, jewelry, morning glow, sunset glow, etc., analyze the characteristics of each original thoroughly, and know well

1. For the manuscript with landscape as the main color, first open the level and remove it with the background color as much as possible, because the composition of landscape gray is relatively small, it should be dominated by three primary colors, and the black version only makes the level foil. Distinctive manuscripts, such as morning glow, sunset glow, rainbow, backlight photography and other works, should have an exaggerated atmosphere

2. For the manuscript dominated by flowers, pay attention to the prominent basic colors, saturated and bright colors. The proportion of opposite colors should not be set off too little, should be kept between 18% and 25%, and the black version should also be properly retained

3. For the manuscript dominated by characters, try to use "image/adjustment/curve" to adjust the proportion of color. Whenever the skin color is adjusted, if the dark field cannot reach the gray balance, the black block in the "optional color" of "image/adjustment" can be used to compensate for the gray balance of CMY's dark field, but it should not be used too much, otherwise color leakage will occur

the gray block in the "optional color" menu can be used to adjust the special originals that are extremely poor and have no color. If you choose the place close to the gray in the figure to adjust the gray balance, the color in the figure will also be enriched. But it should be combined with a variety of tones

it is worth noting that the "optional color" function can only be used as compensation, and the adjustment value should not be excessive, otherwise there will be excessive color correction. Even if the adjustment is large, it can only be in the range of 0 ~ 100 (except for special originals)

4. For dark, medium tone and thick originals, it is best to choose "image/adjustment/curve" and use S-shaped curve to adjust. When shooting this kind of manuscript, because the foreground is too much light, the color is very light, and the depth of the scene is very dark. For example, at the scene of an indoor meeting, because the flash index is not strong or affected by the on-site light, the characters on the podium are unclear and fast. Use S-shaped curve to narrow the contrast, Then carefully adjust the required value

5. For thick originals, select "image/adjustment/curve", and reduce the color curve by 5% at 75% of the curve, or reduce a color curve with color deviation separately. When adjusting, be sure to achieve the balance of hierarchical colors. In other words, use the "image/adjustment/hue/saturation" function to adjust the hue, brightness and saturation, and the adjustment value is within 5

use color balance to make complementary adjustment to the color biased originals: the adjustment values of C, m, y, R, G and B are within 15, and the change of the influence value is between 2% and 3%. Use the steepness of the highlight curve to adjust the flat, gray or low contrast originals. This kind of manuscript has a large highlight and grayscale, which is generally about 10%, and 10% can be adjusted to 3%, so that the light receiving part is bright

6. Using the curve of RGB color mode to adjust the originals with large color deviation, middle note, dark tone and thick thickness, or the originals taken by digital camera, and the downloaded originals can get better results. This is because the color space of RGB mode is composed of additive method, which has a wide color gamut, and it is easy to feel the change effect of color visually. After having the color feeling, it is converted to CMYK color mode for fine adjustment

7. For the underexposed image of the main body in the picture, you can adjust it in the following way: execute the "image/copy" command, copy a new file, change it into gray mode, set it with Gaussian blur, and the value is 3 ~ 6. Return to the original file, use "select/load selection", and select "grayscale" in "channel"; Select "invert"; Select "new selection" in "operation". Close the copied file, use the "/fill" command in the original file, and select "50% gray" in the dialog box "in use"; Select "color fade" for "mode" and set "Opacity" to "100%". Through the above steps, the picture can achieve basically satisfactory exposure results

8. Select "image/adjustment/change" to adjust the saturation of the adjusted originals with rich colors, such as rainbow, morning glow and sunset glow, slightly to make their colors Fuller, brighter and thicker

9. For thinner originals, you can create a new layer by copying the original in the "layer" panel, extract 25% - 30%, and superimpose it on the original in a negative way to thicken it

in a word, only by using the "image" menu in Photoshop, operating from various channels, and combining scanning with computer application software, can we do our best to improve production efficiency. By constantly summing up experience and mastering essentials in practice, the operation can be handy and applied freely

source: keyin