Pursuit of "perfect" film dot repair technology

——Talk about the driving force of “perfect dirty repair software” to practical CTP

The manuscripts of the attached film are scanned and inserted into the layout and output. This is often used in remote transmission of newspaper layouts in the early stages of prepress digitalization. Now, when CTP gradually replaces traditional platemaking, this technology becomes increasingly important and will become a whole. The key to digital success or failure. The key to the standardization of the digitalization process of the linked manuscript is the actual restoration of the site. The closer the site is restored to the manuscript, the more the technology can replace the traditional optical platemaking process. The more direct the computer can represent the practicality. However, in addition to the mature use of selective scanners and their COPYDOT technology, the true restoration of the originals on the screen is another important point in the performance of the dirty-repairing of screen-mounted films. Early "repair" work is usually handled by a simple image processing system, and the general image processing software usually lacks professional processing of the dot processing of the attached film, often leaving the function of "repairing dirty" in the ordinary " On the level of "defective processing", the repair of outlets, especially the handling of colored four-color films, is often at a loss. Recently, the “Perfectin” software developed by Danish company Escofut is a professional image processing software for film scanning. Its appearance undoubtedly brings a new impetus to the current CTP's full practicality.

The New Features of "Completely Dirty Professional Software"

The original purpose of "Dirty Dirty Professional Software" was designed to address the characteristics of the scanned dot image. The best format for film scanning on the grid is basically located in the "bitmap" format of the picture due to its special form of expression. The processing is based on this format. When the film reflects a four-color image, the synthesis of the “four-color bitmap” shows the great advantage of this software. We used the image processing software division from the past. Photoshop in the same situation on the processing method of the network point of view to describe the unusual place of this software.

(1) Restore the backbone of the real network, supplemented by a variety of function selections, and fully realize the digital purification effect of the original network.

When ordinary image processing software uses its own "filter" (such as photoshop's filter filter) to identify "dirty spots" ("dot spots"), it usually selects the range of "dirty spots" and cannot take too much value. Otherwise, fine dots are misjudged as “dirty dots” and are filtered out to make the finished product appear “absolutely net” phenomenon; and the “dirty dots” appearing in the blank areas need to be selected from one area to another, and the area-by-area clean-up is inefficient; The “dirty dots” in the “Dirty Dots” are difficult to recognize and clear due to the adhesion to the dots. For example, manual repairs are performed in the form of pixels. The workload is huge, and the dot shapes that are repaired are different, which directly affects the quality of the copy of the original film on the finished product.

"Perfect Perfection Professional Software" (Perfection) provides four kinds of filter tools based on the use of filters in general image processing software, and for the related factors such as the shape of the film amplitude modulation screen, the number of screen lines, and the screen angle. :Autoclean, dustfllter, Dotclean, Rexample, to achieve the perfect situation with the net compensation calculation of the processing originals. The “dotclean” “dotclean” is to automatically analyze the “dirty dots” between “dot points” to remove black dots that do not belong to the “dot points” and to give the edge a smooth correction according to the shape of the “dot points”.

This kind of correction also takes into account the transitional changes in the “dot points” that represent “grayscale changes.” Therefore, the design of this function is like “finishing the finishing touches” for the entire “renovation” work, and becomes the key to the digital purification of linked manuscripts. With the help of other filters, it is a breeze to get dirty.

(2) Using novel processing methods to break through the limitations of the standard image format, the "repair" feature really becomes highly efficient.

Film scans must use high-resolution "bitmap" input to have high dot-reduction characteristics. We have previously demonstrated this through multiple trials and special treatises. Therefore, all image processing software that invokes this large resolution graphic is required. Faced with the speed and efficiency of the process, PhotoShop is no exception. When the film is a color content, four large-capacity "bitmaps" reflecting four colors are processed at the same time, causing problems for ordinary image processing software such as Photoshop.

On the one hand, the image format does not have a specific color image format in which the four-color “channels” are all “bitmaps,” because the color format of a standard multi-channel color image must be a “grayscale image” in order to process it. When “dirty” is conveniently displayed, it is necessary to convert the “bitmap” format of each color to a “grayscale” format. This is the process in which the space occupied by the image conversion is increased sharply after converting to a “grayscale map”. 8 times to "bitmap"! Take the 8-shot film as an example. When scanning at 900 dpi, the color of the “bitmap” file is 12.5 megabytes per color. When converted to “grayscale”, the file is increased to 100 megabytes per color. The synthesized four-color file is Up to 400 megabytes. Such a high capacity requirement imposes high requirements on the computer used to process pictures, whether from the memory or the central processing unit. In actual use, we encountered the phenomenon of "deadness" caused by the high occupied space of pictures. Therefore, the conventional image processing software has a problem of "too low efficiency" when processing a film scan image.

On the other hand, the ordinary image processing software needs to return to the "bitmap" to provide the layout insertion output after undergoing the color correction of the color film color pattern. It needs to go through the "bitmap", a "grayscale image" and a "bitmap" after passing through. Two conversions result in pixel loss, especially highlights. However, using the CMYK TIFF format instead of the second one makes the file too large, the photo-taking time lengthens, and the second-time screen-hanging is likely to cause loss of detail and moire.

"Perfection" shows the level of professional film scanning and purifying. The software processes color film images directly on a variety of "bitmaps" and displays them on the screen in a "simulation" format so that "dirty" processing can be performed without increasing the file size. Fast and space-saving, at the same time, the direct storage after the repair of the network makes the pixel quality without any loss, completely breaking the limitations of the standard image format, can be described as a major breakthrough in film dirty technology.

"Dirty" software parameter settings and its actual effect

"Perfection" makes the digitalization of the film into the process simple and successful, which undoubtedly brings confidence to the current CTP towards real practicality. We carried out repeated debugging when scanning large-format scanner ESCOSCAN1724 film "repair dirty", and gained a little practical experience, and that the key to "repair dirty" technology is to adapt to the different conditions of film cleanliness and dot pattern, call different filters And adjust the parameters to bring out the best results. Below we will make an introduction from the different performance and parameter settings of each filter.

(1) Autoclean filter features and its parameter settings. Mainly used for the removal of text visceral spots under a blank background.

The "Radius" parameter determines the size of the removed dirt, the appropriate value is 3-4, the maximum is 6, when the size of the text is significantly larger than the size of the dirty point, the pixel loss in the text will be minimal;

"Threshold": 1% to 100% of the range, preferably set to 50%, when the black pixel value is greater than 50% will produce more black pixels, the effect of the final text thickening, dot Expanding, when it is less than 50%, the opposite is true.

(2) dustfilter filter characteristics and its parameter settings. The main advantage of the removal of text viscera is more than Autoclean's detailed parameter settings. The biggest advantage is that the removal of dirty points also ensures the shape and size of the mesh.

"Radius" parameter value of 1 - 10, usually should be set to a lower value, but greater than the dirty point radius, avoiding the filter effect is too heavy, so that the network is destroyed;

“Interactive Threshold”: When this item is checked, the following high/low thresholds will turn white, and the high thresholds will turn black, but the inter-area network points will remain unchanged;

"Recovery points": This function is used to reconstruct the data that you do not want to delete during the filter processing. This function checks which data is modified by comparing the data using the filter area. Once you find the black pixels around the changed black Pixels, then the black pixels will be expanded to reconstruct, such as the edge of the dot, the outline of the text, and so on. Because the dust filter is operated at the level of the pixel, the filter settings should refer to the scan resolution and number of screen lines, dot size, and the number of pixels per mesh.

(3) Dotclean filter features and its parameter settings. The filter is the core technology of the entire dirtying software. It is mainly used to clear the dirty points in the amplitude modulation net point, and to restore the dot point according to the shape and size of the dot. The parameter settings should be based on the resolution used during scanning. Make adjustments.

"Size" parameter: related to the size of the dirty point, should be slightly larger than the radius of the dirty point, the time required for the filter processing and the "size" is proportional to the relationship, the larger the size, the longer the processing time, the general dirty point 5-10 seconds , big may take 50 seconds;

"Effect": A relative value that controls the degree of effect of the filter.

"Recovery Shape": This is a key parameter setting. When using the built-in Moire filter and the value is 0 when scanning film, Dotclean will rebuild the Moire you removed during scanning. Effect; and when you want to remove a large number of dirty points in the dot area, the value of 0 is very good;

"Restricted Area": ​​When selected, Dotclean will not consider map points outside the constituency when analyzing it;

"High-precision reproduction": When selected, the "repair" software will analyze the 4th pixel with the default settings to obtain a higher accuracy, dedicated to the dot reproduction of the low dot percentage area, such as when only a few dots per dot For a pixel, the filter processing time will be longer.

(4) Rexample filter features and its parameter settings. This filter is used to change the output size of the scanned image, either as a long or wide change, or as a scaling. This technology is less practical, because the density of the large original screens for film scanning should not be arbitrarily changed to prevent the screen from being deformed or distanced from the number of screens of the full-length back-end screen, and also to prevent turtles from being photographed. Pattern or hit the net and other phenomena.

Of course, Perfection Professional Software (Perfection) is still being constantly improved and adjusted. Attention should be paid to its shortcomings during use. For example, Dotclean cannot be used for dirty text or lines, especially when dealing with dots. In areas with text, the text must be circled. Otherwise, the text will be misunderstood as dirty and processed to produce text distortion or text plus white nets. In spite of this, "perfect repair of dirty professional software" due to its outstanding technical expertise, has been combined with the film processing related to the 51-year maturity, the quality of the digital processing of the attached screen film into the full-page output can be reliably guaranteed. The convergence of a technology has filled the gaps in the CTP area and has brought profound effects to the overall development of the CTP.