Pre-press color pictures of the best modalities for dealing with
Pre-press color pictures of the best modalities for dealing with
The final quote from the sleeping Grasshopper on 2009-12-4 03:27 PM edit
In the newspaper’s typesetting process, often encountered in the processing of color images, when opening a certain color picture, it might be RGB mode, it could be CMYK mode. So, when using Photoshop is to use RGB mode, or use the CMYK color mode images handled?
The use of Photoshop in the process, we must first note that, for the opening of the picture, whether it is CMYK mode or RGB mode, do not these two modes to switch between each other, let alone the two models will be transferred from switching to the . Because, in the dot matrix image editing software, once for each image color space conversion, will lose some of the details of the original image information. If a picture for a while turn into RGB mode, while conversion to CMYK mode, then the picture is a great loss of information. It is worth recalling that the color used in the process of newspaper publishing pictures lithography model must be CMYK mode, otherwise will not be printed. But it is not carrying out image processing mode of dealing with pictures in CMYK printing effect is certainly very good, but also determined under the circumstances. Processing images using Photoshop select RGB mode stronger than the effect of CMYK mode, RGB mode as long as handle a good photo, and then convert it to CMYK mode output of plate-making film can be printed.
In the image processing, if the handle to open the picture itself is RGB mode, or the original image input process using the scanner lets you select RGB mode scanning, under such circumstances, color newspaper layout is better. Scan of the original picture using Photoshop as long as the File menu bar option in the RGB color settings option to set options through the input color image scanner RGB mode shall be pictures. In short, do not need the first image pattern on the transformation of circumstances, have access to the RGB mode the picture, you use this mode of image processing, especially from the Internet to download images, in order to ensure that the picture printing effect, it must using the RGB mode processing.
1. RGB mode is that all devices based on optical principles used in color mode. Display, based on work in RGB mode. The range of RGB color model is greater than CMYK mode, so, RGB mode can display a number of colors, especially bright and bright colors (color display must be corrected) This is also the image color model from RGB to CMYK conversion when the screen will darken the main reason. RGB mode in Photoshop to edit pictures, you must select View menu CMYK Preview command (if you are using Chinese version of Photoshop, then select the View menu bar of the preview option, select the option to CMYK), that is , using RGB mode editing images to CMYK mode display pictures, so that the operator can see the picture on screen color, that is required when printing colors. Photoshop in CMYK mode, the RGB color channel more than one, its use RGB to simulate the display of CMYK display effect, but CMYK’s calculations based on completely different principles of optics RGB, therefore, to use CMYK mode dealing with pictures of some less efficient to deal with poor picture quality, but also a number.
2. Processing images using Photoshop, some Photoshop filters in some of the models do not support CMYK. In addition, photo editing is often after many subtle processes, such as the contents of several images combined together, as the various components of the original colors can not be the same, they need to be adjusted so that all parts of synthesis in some way to carry out filter processing. As the RGB color model is much greater scope than the CMYK mode, so as to RGB mode of dealing with pictures in the entire editing process, will be a broader color space and a more subtle effect of changing the editor, and these effects, if used well, most can be preserved. Although the final will still have to convert CMYK color mode and will certainly be lost, but it began to let more than one color is missing, or much better picture.
3. RGB mode images will be converted into CMYK mode image, the color separation parameters of the effect of conversion will be good or bad image to play a decisive role. The adjustment of the color separation parameters largely affect the image conversion, Photoshop image processing software have the ability to control the parameters of the color separation. When you need to RGB mode in dealing with a good image will be converted to CMYK mode output, during the conversion process through the adjustment of color separation parameters and switching modes reduce in the image when the color is lost.
4. For the purposes of newspaper publishing, using images require long-term retained in order to retain picture RGB mode is more ideal. After school and amendment of the RGB color model of image data can be an effective long-term storage of documents, so that retrieved from the archives of the RGB mode images can be used in different output devices. For the RGB mode image data and information flow in the future a lot of work to be re-used, regardless of color separation method is used system-level color management method or use of Photoshop’s image conversion method is very convenient.
5. The use of a variety of printers, digital proofing device or a computer monitor for image printing, proofing, output, observation (and measurement) than printing copies of the image output device of the color of the main method is to measure the difference between the neutral gray of the need to produce blue, magenta, and yellow volume, known as gray balance reproduction system. If the picture is converted to CMYK mode, re-use a different output devices, the picture will require high light adjustment CMYK images, in the middle to reconcile the dark tone outlets, changing the overall gray balance and color saturation. In order not to affect the image printing quality, the amount of black on the picture to be changed, but if revised data printing black pictures, will produce undesirable printing results. For example, the original color separation for high-quality sheet-fed printing press of the CMYK mode image, if the web printing presses will cause rubbing dirt on the phenomenon of large amount of black in the picture of the point, treatment can only be amended CMYK mode. The RGB mode image can use a larger range of RGB colors to reproduce a more brighter, more saturated colors.
Through the above discussion we can see that dealing with the use of Photoshop to make use of RGB color images should model. It should be noted during the operation: Use RGB mode image processing must be to ensure that the model output with CMYK colors when the authenticity of images; the use RGB mode in dealing with pictures make sure your pictures are completely handle and then converted to CMYK mode image, the most Good for those who stay an RGB mode image backup.
In addition to using RGB mode in dealing with photographs, Photoshop’s Lab color model with good features. RGB model is based on optical principle, while the CMYK model is the reflection of light paint color mode, Lab advantage of this pattern is that it makes up for less than the previous two kinds of color patterns. RGB at the transition between blue and green color too much, the transition between the green and red color too little, CMYK mode of dealing with pictures in the editing process of the loss of color is more, and Lab model in these areas, compensated. Lab model composed of three channels, L-channel that intensity, which controls the image brightness and contrast, a channel included in color from dark green (low brightness values) to gray (in brightness values) to the bright sub-red (high-brightness value) , b-channel, including the color from bright blue (low intensity values) to gray to yellow-focus (high brightness value). Lab mode and RGB mode is similar to color mixing will result in brighter colors. Only the value of the luminance channel only affect the color changes of light and shade. Lab mode can be seen as a two-channel RGB mode plus a luminance channel model. Lab model is device-independent, and can use this model to deal with any one image editor (including the Gray map image). Lab mode can guarantee that when the CMYK color mode conversion within the scope of color suffered no loss. If the RGB mode images into CMYK mode, the steps should be coupled with an intermediate step, that is, first converted to Lab mode. In the non-colored newspaper typesetting process, the application of Lab mode will convert the grayscale image is often used. For some of the RGB model on the Internet to download pictures, if that is not converted to Lab mode and then transition to grayscale, then use desktop publishing software, Founder FIT, or Risperdal row of newspaper version, and sometimes the pictures can not be typeset.
Thus, in the editing pictures, as far as possible the first use Lab mode or RGB mode, as a last resort when converted to CMYK mode. Once transferred into CMYK mode image, can not easily turn back again, and if really necessary, would turn into a Lab model image processing. If the input for scanning the original picture is in color images, but the picture is used for gray-scale layout, and use a scanner to enter the picture, do not directly input the original image to grayscale mode, should be RGB mode input images, using RGB mode in dealing with a good photo, will be its first picture is converted to Lab mode, and then through the channel separating the command, select the L-channel image as a grayscale image printing.