When designing print manuscripts, no matter what color mode is used in the pre-production, the final color mode is usually bitmap, grayscale and CMYK mode (the color mode of the spot color channel is special, and its color gamut range is relatively large). Therefore, color mode conversion is particularly important in the prepress production process. (PhotoShop CS software is used as an example in this article)
1 RGB mode to CMYK mode
Open an RGB picture with Photoshop. When we click the menu "View \ Color Gamut Warning", a gray part appears in the pattern. Because in the process of converting RGB to CMYK, the color gamut of RGB is larger than that of CMYK, the image may have color overflow phenomenon, which will cause the loss of color. The gray part is the color overflow range in the image.
Then, if you create a new file, define the color mode as CMYK, so that all colors are within the range of CMYK color gamut, there will be no color overflow. However, in CMYK mode, Photoshop has many effects. Filters are unavailable, and at the same time, they cannot meet the color separation process in some special cases. Therefore, in the early stage of making print design drafts, it is best to use RGB mode for images to facilitate our adjustment and processing. Until the entire design draft is basically completed, come to CMYK. Let all kinds of color modes give full play to our design.
2 Color mode to gray mode
Compared with RGB to CMYK, there are more methods for color to grayscale, but different methods of operation also render the final grayscale differently.
1) Color RGB or CMYK images are directly converted to grayscale mode. Our most commonly used method is to directly click on the Photoshop menu "Image \ Mode \ Grayscale". This conversion method does not consider any image conditions. The converted grayscale image is darker overall, and the brightness of the midtones needs to be improved by adjusting the curve or the color scale.
2) Use channel mixer. Open "Image \ Adjustment \ Channel Mixer", select monochrome, and then adjust the value of the corresponding source channel to adjust the gray level you need.
3) Turn to gray after removing color. First, the RGB image is decolorized so that it is displayed in grayscale, and all color information is neutral. Then switch to grayscale mode.
4) After switching to Lab mode, take out the L brightness channel as the grayscale image. First convert RGB to Lab mode and check Lab channel. Delete the two channels a ､ b and keep only the L channel. At this time, the L channel becomes the Alpha1 channel. At this time, we can click "Image \ Mode" to see that it is a multi-channel mode, and then convert the multi-channel mode to grayscale mode, and get the grayscale pattern from the L channel in Lab mode.
5) In the channel panel, select a channel that is cleaner and has a gray value that meets the requirements to convert to a gray image. I can click the R ､ G ､ B channels in the channel panel to select a more suitable channel and copy to generate a copy. Then delete the R ､ G ､ B channel. After deleting, click "Image \ Mode" to convert the multi-channel mode to grayscale mode.
The gray patterns obtained by the above 5 methods, we view them separately through the histogram.
We see that the grayscale images obtained by methods 2) and 4) are fuller and the image is softer. The grayscale images obtained by the other three methods require a series of adjustments such as color scale and curve to obtain a more delicate image texture.
Single Rotor Watch Winder
Rotating Watch Box,Versa Watch Winder ,Best Watch Winder,Automatic Watch Winder Box
GUANGZHOU T.WING-PAK MFG.CO.,LTD , https://www.twing-pak.com