In the newspaper publishing process, often met on the color image processing, a color when you open an image, it could RGB mode, it can be CMYK mode. So when the use of Photoshop in RGB mode or CMYK mode for color images using it used? This article talk about the author views on this subject.
With Photoshop with images of the process, the first that should be observed for the opening of an image, both CMYK mode image, picture or RGB mode, not switching to another between the two modes, even at two models and turn. For in the lattice image editing software, once for each image color space conversion, loses a part of the original image map. If a picture is turned on for a while in RGB mode, while the conversion in the CMYK mode, then the picture would be a great loss of information. It should be clear that the process of the image for color newspaper printing plate making mode must be CMYK mode image can be published, otherwise it will not be printed. But not to say that the implementation of image processing mode when processing images in CMYK printing effect certainly be good, or should be under the circumstances. In fact, the Select with the Photoshop image to RGB mode results better than those with the CMYK mode, RGB mode, while processing the image, then convert them into CMYK mode image plate, after the output can be printed film be.
During image processing, when the open processing of the image itself is RGB mode image or the original image input process with the scanner you can scan RGB mode, select the layout for this newspaper, the color is best. When scanning the original image with Photoshop, as long as the menu bar, select the option file in RGB color options, the input color image scanner RGB mode the picture is selected. In short, without first getting the image transformation mode to transfer the case to the RGB mode the picture, use this model in image processing, especially the images downloaded from the Internet have to ensure that the image of the pressure effect , it must be processed with RGB mode. From the following aspects of the exhibition to illustrate this point.
1st RGB mode is all the equipment based on optical principles used in color mode. Such as monitors, RGB mode based on the work. The RGB color model palette is larger than CMYK, so RGB mode, the performance of many colors, especially the vivid and brilliant colors (of course, the color display and calibrated, and it does not show picture coloring). This color in printing is difficult to obtain from India. This is the image color mode conversion of RGB to CMYK screen darkens, if the main reason. RGB mode in Photoshop to edit the image, you must first in the View menu in the CMYK Preview command (if you use the photo shop for the Chinese version, then select the View menu bar of the Preview option , select one of the CMYK options that can), that is, edit images with RGB and CMYK mode to display images so that the operators of the screen to see the colors, actually the color printing needs, this is applied very important in order to have a good time of going to this image processing method. Photoshop work in CMYK, RGB color channels, one more than the others, it is appropriate to use RGB to CMYK display simulated results and CMYK-based optical computing method and the RGB completely different principle, that is, CMYK mode of dealing with pictures of some less efficient should deal with the image quality worse.
2nd Processing of images with Photoshop, Photoshop some, not some filter does not support the CMYK model. In addition, the imaging process often takes many subtle processes, how can a few pictures of the contents of the portfolio will, together, not as components of the same original color require them to adjust, it can form part of the synthesis in some way and to filterand much more. No matter what achieve the vision, results, operators want to generate as much as possible and keep all kinds of subtle effects as far as possible, so that the screen has a real and rich in detail, because the color palette of RGB mode is much larger than the CMYK mode, RGB mode, and therefore with pictures, in the formula is, can a broader color space and a more subtle effect of a change of editor, and the effects, if used, most are well maintained. Although ultimately convert to CMYK color mode, and will certainly be lost, but this picture than in the beginning is much better color loss.
3rd In RGB mode image into CMYK mode image, the color separation parameters of the effect is good or bad image conversion played a decisive part. Parameterization of the color separation, have found a great influence on the image conversion, Photoshop image editing software control on the color separation parameter. That is, if you need a good image editing in RGB mode to CMYK mode output, while the conversion of the adaptation by the color separation parameters, the mode conversion in the color image is lost should be reduced.
4th Currently, for newspaper publication, the pictures in a long-term commitment to RGB mode used to retain image data is ideal. After color correction and amendment of the RGB image data can be an effective long-term storage of documents to retrieve in the future from the archives of the RGB image can be used in a variety of output devices. RGB image data for the next game in the works to be used again, regardless of the color separation is to system-level color management method or the use of Photoshop image conversion method is very convenient.
5th With a variety of print, digital proofing device or computer monitor for photo printing, proofing, output, observation (and measurement) above the printed copy of the image output device color difference to produce mainly by the need to measure a neutral gray blue , magenta and yellow as the content, print-copy system gray balance. If the image is converted to CMYK mode, then re-use of different output devices, requires the adjustment of the image CMYK image with a high, dot the mid tones and shadows, and change the entire gray balance and color saturation.In order to not affect the image quality, the amount of black on the image to be changed, but if the data is changed black print image, print the result will be negative. For example, the original high-quality sheet-fed printing press of the CMYK color separation model image, if a web-printing machine leads to rub dirty appearance, a large picture of a black point, treatment can only be changed CMYK image mode. The RGB mode image can be used to a wider range of RGB color even brighter, more saturated colors. However, as the CMYK color separation in the picture is, after all the pixels in the image in the CMYK color space.
Can be shown by the above statements, you should use Photoshop for color RGB mode.However, should be observed during the operation: the use RGB mode image processing has to ensure that the model output with CMYK colors when the authenticity of the image using the RGB mode of dealing with pictures sure that picture has been completely processed make and then converted to CMYK mode image, an RGB mode is best left is image backup.
In addition to using RGB mode, the processing of photos Photoshop Lab color mode is also good. RGB model is based on optical principles is based and CMYK color model is the color of reflected light mode Lab advantage of this design is that it makes less than the first two color mode. RGB at the transition between blue and green, too much, the transition between green and red color too little, CMYK mode image in the process of editing is the loss of more color, these aspects in Lab mode of compensation. Lab model of the three channels, L-channel, the intensity, the brightness and contrast of a channel, including the color of dark green (low brightness) to gray (in brightness) to sub-red light (high luminance value), B-channels, including the color of light blue (low intensity value) to gray to yellow Focus (high-brightness value). Lab mode and RGB mode is similar to mixing will result in brighter colors. Only the brightness values of channels changes only affect the color of light and shadow. Lab mode can be seen as a two-channel RGB mode, and a luminance-channel model. Lab mode is device, this model can not be any editing (including the gray card), and RGB mode with the same fast, faster than the CMYK model is many times. Lab mode can guarantee that if the CMYK color mode conversion within the color is not lost. If the image in RGB mode and CMYK color mode, steps should be added as an interim step that is first converted to Lab mode. In the non-colored newspaper publishing process, the use of lab-mode image into gray image is used frequently. For some of the Internet to download the image RGB mode, if not converted to Lab mode before the transition grayscale, then increase with the founder or risperidone newspaper publishing software version number, sometimes not on the image layout.
So in image editing, use the Lab as the first mode or RGB mode, convert to CMYK mode of last resort. Once transferred into the CMYK image mode is not reverse as easily, if ever, need to turn in Lab mode, the image processing. When used at the input of the original image scan is in color, but the picture used is for gray-scale layout, and use a scanner, enter the picture, not the original image directly into the gray model, if image with RGB mode, edit mode with ENTER RGB image to convert the Lab mode before the image, and then through the channel separating the command, choose the L-channel of the image as a grayscale image printing.
Most market participants in the actual process of dealing with pictures, are relatively simple, and what a picture on the scanner, scan directly into the view mode, and then after a little treatment for the comp, look also at the time of print or something. In fact, at a really good picture, or do not bother printing effect, in accordance with standard steps.