Commonly used image processing software has its own characteristics. If beginners do not master some details of various software, they will often lose due to some mistakes in the operation. In the teaching process, the author often encounters students who are unable to output the whole work or other problems due to some details. Combining years of teaching experience with prepress graphic processing software, this article discusses and summarizes the precautions for the use of several commonly used graphic processing software, and hopes to share it with readers.
1 Notes when using Photoshop
1) It is best to use RGB mode during image processing
â‘ Don't change the color space randomly during use, this is because part of the color information will be lost every time. Since the final output is in CMYK mode, it can be processed in RGB mode. If the display is in CMYK mode, you only need to set it in "View / Proof Setting".
â‘¡The color space expressed by RGB mode is larger than CMYK, and the file is smaller than CMYK, and the file processing speed is much faster. When processing images in RGB mode, you will get a wider color space and more variable editing effects. Although it must eventually be switched to CMYK mode, and there will definitely be color loss, it is always better than losing image color from the beginning.
â‘¢All filters can be used in RGB mode, but many cannot be used in CMYK mode.
2) The method of color space conversion
①RGB → LAB → CMYK? Make RGB file backup before conversion.
②RGB → LAB → Grayscale? Use Lab's "channel separation" command to convert the grayscale image.
3) Matters needing attention before output
①The resolution should be ≥300ppi.
â‘¡Merge layers, delete redundant paths and channels, save the file format as uncompressed TIF or EPS, and images with larger graphics should be stored in EPS format.
â‘¢ Make sure the image mode is CMYK mode. The image used to print the film must be in CMYK mode, so the image mode must be converted before the film is printed. However, the CMYK mode does not have a wide color gamut of the RGB mode. The RGB mode is generally used in the image processing process. After the processing is completed, the image mode should be checked and the conversion result should be checked to ensure that there is no color cast before output. If there is a color cast, the color mode conversion should be cancelled immediately, and it should not be converted back to the RGB color mode, otherwise it will cause more color loss.
â‘£ Make sure that the solid background (such as pure yellow, pure black, etc.) has no other noise.
⑤ The text description in the picture should not be done in Photoshop. If it is a printed page, it is better to use different software to process the image, graphics and text separately.
â‘¥ Black and white images, if no special requirements, generally in grayscale mode. For line draft images such as bar codes that must be expressed in the form of dot matrix images, the general resolution is not lower than 1200 ppi, and the color mode is binary (Bitmap). Furthermore, the dot matching is also a very important issue that affects the image quality. For the CMYK dot matching situation of contrast, dot size and gray balance data, it must match the subsequent printing process.
For example: printing with offset paper, the general dot contrast is between 5% and 85%; if it is printed on coated paper, the dot contrast is between 2% and 98%.
2 Precautions when using CorelDraw
1) Image processing in CorelDraw
â‘ Rotate, mirror or tilt the image and the shadowed image, and it needs to be converted into a bitmap.
â‘¡ If the image in the precise cropping frame is rotated or the resolution is different, it needs to be converted into a bitmap.
â‘¢ In addition to the bitmap in the above situation, the RGB image can be directly converted to the CMYK mode (do not select all the RGB images together, because there may be some pictures that are not on a layer, and some strange problems may occur after conversion);
â‘£The image with the filter needs to be converted into a bitmap? Note: Does the original image change too much after conversion?
⑤ When accurately cutting the bitmap in the picture frame, you should also pay attention to the above problems, and also pay attention to whether the frame is locked with the image. If not, please lock it.
2) Graphics processing in CorelDraw
The problem of graphics is relatively much less. The most important thing is the transparency problem. The graphics that use the transparency effect are prone to problems during output. Therefore, it is best to convert the graphics with transparency effects to bitmaps. But sometimes, when there are thousands of pictures in a file with transparency effect, it is best to select a few representative graphics to convert to bitmap to see, if there is no big change in the graphics, such as conversion After losing things, you can try not to change. If the graphics use other effects, you can ignore them. [next]
3) Problems with fonts in CorelDraw
â‘ Fine art characters should be converted into curves.
â‘¡ Try not to use the GB2312 font. After this type of font is converted into a curve, there will be obvious hollows where the strokes cross; Founder's beautiful black does not turn the curve.
â‘¢ Sometimes the system will falsely report missing fonts, but if you open the file, if the save button is gray, it means that there is no missing fonts (if not, honestly install the fonts and restart it).
â‘£The font should not be drawn too thick. Otherwise, although it looks normal on the computer screen, there will be different degrees of "jaggies" in the output, which will cause some loss to the output.
⑤ When the font turns into a curve, it crashes, indicating that there is an art text in the precise cutting frame, so pay attention.
â‘¥ Paragraph text, you should pay attention to whether the text in the text box is all displayed (it is easy to overlook).
⑦The next is the most troublesome problem. Enter the text in the full-width state. If there is a space typed in the text, then you will find that the text you entered is gone after the film is released. Open the file at this time and search with Find Art Words, you will find that there are places where the search for Art Words is found, but all are a row of small hollow dots. This is the problem of the disappearance of the font that appears in the spaces entered in the full-width state as mentioned above. The only solution is to use Chinese and English fonts to check what the word is, and then restore the text. If there are no words displayed in Chinese and English fonts, it means there are only spaces and no words, then Delete can be deleted, or replace them with half-width spaces when outputting errors.
4) The processing method of font effect
â‘ If you use the zipper or the envelope, you can turn the curve without paying attention.
â‘¡Outline characters, all fonts can be selected and the outlines are separated together, then the fonts turn to curves.
â‘¢ The three-dimensional characters are also separated after being selected together, and the font turns into a curve. Note that the following three-dimensional image is preferably a bitmap.
â‘£ If the font is rotated, please select it and separate it. Font to curve, shadow to bitmap can be transferred.
⑤Art text can generally be turned into a curve with little change. Text words cannot be turned directly into curves. When the text font is converted into fine art text, some characteristics of the text text will disappear, such that the text style becomes unrecognizable.
5) Other places to be noted
â‘ Colored characters: the characters C100M100Y100K100 are used, the original intention is to want black characters, but if it is set like this, although it is also displayed in black characters, but there are characters on each film after the film is printed, there will be printing overprint. Happening.
â‘¡Bringing the corner line: If you want the output device to bring the corner line, the length and width set on the printed page must be greater than the length and width set on the file page by more than 10mm ~ 15mm.
â‘¢ Locking problem: Sometimes, the person who made the picture locked a certain picture in the picture. Generally, you should select all before checking the pictures, and then Ctrl + G to center after selecting all. At this time, if the graphic is locked, it will not be moved, so when checking the picture, check whether any image is locked.
â‘£Print lock: You may encounter a situation, when you want to convert a picture into a bitmap, a prompt box pops up (the objects on the non-printable layer cannot be converted into a bitmap), then you must call up " Object manager "to unlock the print.
⑤ The most commonly used when checking files is "file information", which is very useful when checking.
3 Precautions when using Illustrator
1) Generally speaking, the Illustrator file is large and the output speed is slow. For graphics made with Illustrator software, the accuracy in the "Properties" dialog box should be adjusted to 2400 points, otherwise the image is prone to appear as polygons (that is, it is not delicate enough and has jaggies).
2) When using Illustrator software for typesetting, the text should be converted into a curve, the noise should be removed, and then placed in the group version software for output. Place the image file in Dcs (Desktop Separation) format, you can't choose the embedding method to place in the Illustrator document. During the output, the software will not call the other four separation documents, and the image with low resolution appears.
3) Be sure to use the CMYK map, otherwise you do n’t know what effect it has. Illustrator has the function of converting RGB images to CMYK, but the color effect is extremely poor and the practicality is extremely low. Do not scale or rotate the bitmap, it should be done in Photoshop, otherwise it will increase the time of film production. Some output companies do not support the Eps format of Dcs2.0, it is best to use Dcs1.0 Eps or TIF format.
4) The Illustrator output is an Eps file with black text and graphics to be selected for black embossing.
5) Spot color setting. To use spot colors in Illustrator, you can use the Pantone color supplied with the software or a custom spot color, but the same spot color must have the same spot color.
6) About pattern filling. The graphics fill color must be a single color, not gradient colors or other pattern fills. When you rotate, zoom, mirror, tilt, and move the graphics that use hatching, select the pattern collage deformation in Preference, so that the hatching and the graphics are deformed at the same time. [next]
4 Precautions when using PageMaker
1) Font problems in PageMaker
About text. The first thing is to be compatible with the fonts owned by the output center, that is, the output center has all the fonts contained in the document. Otherwise, the font may not be output.
â‘ In addition to the use of "italics" in the Chinese character effect, other character effects are prone to errors. Especially the "underline" and "hollow effect" can not be realized correctly, "bold" will cause slurs, "hollow effect" font will not be hollowed out, when the Hanyi font uses "underline", the horizontal line will penetrate into the word (square The font can be 'underlined'). If you use a compound font, please bring the compound font file together with the output to prevent the font and content from being inconsistent.
â‘¡ If the Chinese in PageMaker uses bold, it will definitely be an overlapping word with teeth. Similarly, other font effects in PageMaker will have problems. To avoid the above problems, the first thing is to try to use the corresponding text in bold, such as bold Song or big black. In the text effect dialog box, the value of the word spacing cannot be too small, otherwise it will cause the phenomenon of overlapping words. The shadow effect of the font is very different from the actual output after the display, and when the black overprint is selected, the shadow part of the font will be transparent.
â‘¢ Avoid using spaces to align text, use the 'Tab' key and adjust the position in 'Indent, Tab Stop'.
â‘£Sometimes when the text is typeset, there will be a mixture of simple and complex, which may easily cause skipping. For this case, only the method of truncating the text can be used to solve it. When changing fonts, replacing similar fonts between different fonts can easily cause skipping. Vertical text in PageMaker is easy to run, and English fonts in PageMaker cannot be rotated.
2) Image problems in PageMaker
â‘ For pictures, do not do any destructive operations (rotate, mirror, or invert the image, etc.) after importing. If you want to make changes, please modify them in Photoshop before importing.
â‘¡ Ensure that all images have links. Images without link information can only be output at 72dpi. When the PageMaker file is opened, the images are automatically linked in this folder. If different images with the same name are placed in different folders, the images may be linked incorrectly when the file is opened. At this time, if the linked image is changed, the size of the newly generated file may be different from the original size, so that the image may be deformed after re-linking. To avoid directly copying images or graphics from other production software and pasting them into PageMaker, you should use the 'Place' command to place the graphics or images. Directly copied graphics or images cannot be separated and output.
â‘¢ When placing a large TIFF image or a TIFF image with very high accuracy in PageMaker, the output image is prone to stretch deformation, which can be saved as EPS. After inserting the EPS picture, avoid coloring the EPS picture, otherwise the hair piece will be output according to the filled color or the output color is wrong. The EPS image placed in PageMaker cannot be a JPEG compressed EPS image, otherwise it will be a gray block after output. In PageMaker, EPS cannot be colored, otherwise the screen will not be visible and the film will change color.
3) Page settings in PageMaker
About page setup. The picture or color block on the edge of the page should have "bleeding" of about 3mm ~ 5mm outside the page to avoid white edges when cutting. After the document is created, if the default cutting line and page information settings of the software are used during output, the position of the cutting line is determined according to the "paper size" in the page settings. If the paper size is too small, it may cause the document 'S content cannot be completely output to the film.
It should be noted that the higher the software version, the better, and the higher the version, the greater the number of unknowns. Therefore, you must pay attention to the version during use. If you use a higher version of the software, you must make a comprehensive output. Check to avoid some unknown errors. Now the more mature version of the software is generally a lower version. It is recommended to use the versions listed in the following table for output, which can minimize the probability of errors. In addition, it should be noted that the software used should be the full version. During the installation, use the customized installation format to ensure that all required components can be installed.
The format stored by the software is its own format or EPS and PS. Do not directly output it as a PDF file format. Use the "Print Quality" setting in Acrobat Distiller to generate a PDF file. And use Acrobat's "pre-press check" function to check the file before output, and use the "output preview" function to preview the color separation.
The above is a summary of the author's experience in specific work practices. If there are deficiencies, I hope the readers will criticize and correct them.
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