Bad quality of images using GDI+ with PostScript driver - c++

Question

I'm developing a program to print images of different formats (BMP, JPEG, EMF, ...) on HDC using C++ and Windows GDI+. Using the MS Publisher Imagesetter driver I can generate a postscript file and through GhostScript functions I obtain the PDF file. If I try to print the following image:
I obtain the following bad quality result with those strange squares (not present on original image):
The part of my code that I used to print the image is:
SetMapMode(hdcPrint,MM_TEXT);
Gdiplus::Graphics graphics(hdcPrint);
graphics.SetPageUnit(Gdiplus::UnitMillimeter);
Gdiplus::Image* image = Gdiplus::Image::FromFile(srPicture->swPathImage);
graphics.DrawImage(image,x,y,w,h);
I tried to print the same image with many drivers and different kind of formats (different from PostScript: PDF, EMF, real printer) and the result is always acceptable (the squares are not present).
Furthermore, I tried to open the bad quality result with a pdf reader different from Adobe Acrobat Reader DC (Wondershare PDFelement and Chrome) and, even then, the result is acceptable.
I also noticed that if the image contains some different shapes (i.e. a big red line, like in the next image) the result is good too.
At this point, I have no idea if the problem is Adobe reader or my implementation.
Is there a differnt way to print different formats images with GDI+ (or pure GDI)?
The PostScript file generated is this.

Answer 1

Well... You haven't supplied either the PostScript or PDF files, which makes it really hard to comment.
Its not completely obvious to me at what point you are getting the image you show, is this what you see on the PDF file ? Is it something you are getting when printing the PDF file to a physical printer ? If its the lattter, how are you printing the PDF file to the printer ?
The JPEG you have supplied a link to is really small (6Kb), are you genuinely trying to use that JPEG file ?
My guess (and in the absence of any files, a guess is all it can be) that you are using an old version of Ghostscript. Old versions would decompress the JPEG image, then recompress the image using whatever filter produced the smallest result, usually JPEG again.
Because JPEG is a lossy format, every time you apply it to an image the quality decreases.
Newer versions of Ghostscript don't decompress the JPEG image data when going to the pdfwrite device, unless other optsions (eg Colour conversion, image downsampling etc) make it neccesary. The current version of Ghostscript is 9.27 and the release of 9.28 is imminent, I'd suggest you try one of those.
Another possibility would be that either the PostScript program has been created in such a way as to degenerate every image smaple to a rectangle, or you are using an extremely old version of Ghostscript where that technique was also used.
Note that none of these would, in my opinion, lead to exactly the result you've pasted here, but the version is certainly worth investigating. Posting the PostScript program file (ie the file you send to Ghostscript) would be more helpful, because it would allow me to at least narrow down where the problem has occured.
[EDIT]
The fault appears to be an intriguing bug in Acrobat.
The PostScript program uses a colour transfer function to invert the colour samples of the RGB JPEG image. (this is a frowned upon practice, its not what transfer functions are for, but its not uncommon). Ghostscript's pdfwrite device preserves the transfer function.
When rendered Ghostscript correctly produces the expected result, Acrobat, however, spectacularly does not, I have no idea what kind of mess they've made which leads to the result you get but its clearly wrong.
If I alter Ghostscript's pdfwrite production settings to Apply transfer functions instead of preserving them:
-c "<</TransferFunctionInfo /Apply>> setdistillerparams" -f PostScript.ps
then the resulting file views correctly in Acrobat. If I modify Adobe Acorbat's settings so that it uses Preserve instead of Apply for transfer functions (look in Settings->Edit Adobe PDF Settings, then the Color tab, and at 'when transfer functions are found', set the drop-down to Preserve instead of Apply) the resulting PDF file renders correctly in Ghostscript, and the same kind of incorrectly in Acrobat as the Ghostscript pdfwrite output file.
In short I'm afraid what you are seeing here is an Acrobat rendering bug, you can work around it by altering the Ghostscript transfer function settings as above but its really not a problem in Ghostscript.