PdfCMYKerLite - inspect and remix CMYK separations of PDF file

PdfCMYKerLite is a wxPython GUI front-end for Ghostscript gs and ImageMagick convert, which uses the Ghostscript tiffsep device to obtain CMYK separations of a PDF document, which are displayed in the application. The application then offers a limited possibility to "remix" the CMYK channels (for instance, copy the K channel to the three other ones to obtain a rich black), and then finally uses gs and convert to obtain a rasterized version of the currently browsed page with remixed CMYK channels.

Usage

(1). Choose a path to PDF file to open, by either:

• Using the 'Browse' button on the top bar
• Pasting or typing the path into the 'Open' text field, and pressing ENTER
• Drag & dropping a file anywhere on the top bar

Note that either of these three methods simply set the file path to be opened - but do not open the file directly. When a file path for opening is set, it will be colored gray.

(2). With a file path set, press the 'Open' button

PdfCMYKerLite calls Ghostscript to obtain .tiff thumbnail separations, and shows them in the application. The top part of the application shows the "input" thumbnails: the color image, and then the original CMYK separations of the given file and page. The bottom part of the applications shows the "output" thumbnails: the separations mapped accordingly to the mapping settings, and then a color version derived from the mapped separations. The file path in the top text field changes to black color, to indicate that the file is opened.

(3). Use the numeric spin control (either click on the arrows, or type a number and press ENTER) to get to the page of interest. Each time a new page is set, a new set of "input" and "output" thumbnails is derived and shown accordingly. Also, each time a new page is set, the text field on the bottom of the window is updated with a new PDF output filename (in the same directory as the original file).

(4). Set the output CMYK channel mapping; you can choose one of the mapping presets:

• Orig. K to rich CMYK black - copies the K channel of the input file to all 4 CMYK channels in the output
• Plain black only - attempts to suppress the CMY channels in the original file, so that only the K channel remains in the output
• Identity (passthrough) - the CMYK channels of the output remain identical as in the input file; thus this setting will merely rasterize a page in the CMYK color model, at the given output resolution

You may also want to change the output resolution at the desired ammount of DPI (dots per inch) at this point, by typing in the desired value in the 'Output' text field at the top right of the application. Also, you do not have to use the mapping presets - you can also manually change the mapping for each individual channel.

(5). Confirm the Output PDF file path

If you're not happy with the autogenerated Output PDF file path, you can either:

• Paste or type an (absolute) path in the Output PDF file text field, and press ENTER
• Use the 'Browse' button in the bottom of the window to choose a new output directory and file name (note that pressing "Save" in this file dialog, will not save, but just set the path).

Once you're happy with the output PDF file path, you can now press the "Save" button on the bottom right of the application window - and after some seconds, the output file should be generated. At this point, if you have a valid path to a PDF viewer set in PdfCMYKerSettings.py, it will be started with the output PDF file, so you can inspect the output.

Name

The PdfCMYKer part is because, well, the application deals with PDF and CMYK. The Lite part is because originally I wanted to make this application by pulling in Python API interfaces to ImageMagick and Ghostscript inside the application, and do the rasterization and CMYK channel manipulation through that. However, that turned out to be too much work, so I decided to just make the GUI (wxPython) part of the application call the ghostscript and convert executables instead, and in that sense it is a much more Lite solution than the one originally intended.