AR_GS_ATSCompare < Ghostscript

---+ Comparing Adobe Acrobat vs. Ghostscript ATS Compare

To compare rendering created by Adobe Acrobat with Ghostscript the following process was performed:

   * The ATS files were transformed from their current state to a PDF format that forced the embedding of the fonts.
   * Adobe Acrobat DC was used to generate a 300dpi SWOP CMYK TIFF file for each PDF page.
   * Ghostscript was used to also generate a 300dpi SWOP CMYK TIFF files for each PDF page.
   * Since Acrobat SWOP CMYK TIFF format does not support overprint, Ghostscript TIFF files were generated with oveprint turned off.
   * The resulting Ghostscript and Acrobat generated TIFF files were compared using bmpcmp -w5 -l -t33 which does a comparison with a 5x5 window in CIELAB delta E color space with the a delta E threshold of sqrt(33).
   * The resulting output from bmpcmp was transformed to a form that was suitable for web viewing (thanks Robin!).
   * The results are available at http://peeved.ghostscript.com/mvrhel/bmpout/compare.html
   * At the top of the page and the bottom of the page, you can see a navigation bar to each web page (463 pages).
   * There is also a Next&gt;&gt; link at the top and bottom right handside that will navigate you to the next page.
   * When viewing you will see that each PDF page is broken into smaller parts to allow easier viewing.
   * Each set of three is (from left to right) the Acrobat output, Ghostscript output, a difference file.
   * The difference file shows a colorful encoding of black, green and red.
   * Black regions are no different, green regions have small differences and red regions have large differences.
   * At the top of each PDF page section you will see a link like 5: tests_private/pdf/PDF_1.7_ATS_2013/TestFiles/AC9Z61EC_A-1B.pdf
   * This hyperlink would take you to the actual PDF file that was used to generate the TIFF files
   * The page number of the PDF file for a particular image is shown at the bottom of the image. For example Page=01 PageSize =2550x3300 TopLeft =(1879,59) W=512 H=901 XY
   * Note that each page has a simple html address. For example page 10 is compare10.html

To do:
   * Review each page. Note that Acrobat output is on the left, Ghostscript in the middle, difference to the right.
   * For pages that have red content in the difference make a note of the following:
   1 The html page (e.g. compare10.html)
   1 Reference number of the image (e.g. item 5 for 5: tests_private/pdf/PDF_1.7_ATS_2013/TestFiles/AC9Z61EC_A-1B.pdf)
   1 Make a visual comparison. Do you see a difference in those red regions?
   1 What appears to be the difference? Is there missing content, extra content, item in wrong place, is the color wrong?
As an example, go to http://peeved.ghostscript.com/mvrhel/bmpout/compare2.html and scroll down to item 53. Note that there is a difference. The issue is that the text in Acrobat is bolder than the text in Ghostscript.

Another example is http://peeved.ghostscript.com/mvrhel/bmpout/compare3.html.  Scroll to item 77. Note that there is a color difference in the images. The AR image is lighter and has a different hue than the Ghostscript rendering.

Both of these should show up in a written list with consistent usage so that we can readily see the most common problems.  If you can put in the links that would be great. For example:

http://peeved.ghostscript.com/mvrhel/bmpout/compare2.html , item 53, Acrobat text bolder than ghostscript text

http://peeved.ghostscript.com/mvrhel/bmpout/compare3.html, item 77, color difference in images

We can then readily navigate and do a deeper assement of any issues.

-- %USERSIG{MichaelVrhel - 2020-07-06}%

---++ Comments

<br />%COMMENT%
   * [[%ATTACHURL%/PDF_testing_-_Screencompare.xlsx][PDF_testing_-_Screencompare.xlsx]]: Preliminary testing results
Attachments
Topic attachments
I	Attachment	History	Action	Size	Date	Who	Comment
xlsx	PDF_testing_-_Screencompare.xlsx	r1	manage	18.8 K	2020-07-09 - 15:27	HenryStiles	Preliminary testing results
This topic: Ghostscript > WebHome > AR_GS_ATSCompare
Topic revision: r3 - 2020-07-09 - HenryStiles