Discrepancies in display of JPEG images

[XnTriq]

Can someone please explain why this image is displayed differently by XnView and...

• Corel Photo-Paint 11
• Macromedia Fireworks 4
• MediaChance Photo-Brush 3
• IrfanView 4
• Cerious ThumbsPlus 7

... as compared to...

• Adobe Photoshop 6
• Micrografx Picture Publisher 9
• Jasc Paint Shop Pro 9

XnView vs. Paint Shop Pro:

• 
  [ z00m ]

[Drahken]

It appears in your sample That xnview is applying some sort of antialiasing that psp9 isn't. Are you using a resample/high quality zoom filter in xnview but just plain zoom in psp9?
I can't run a direct test myself, since I don't have any of the 3 progs in your second list. I do have psp7 though, I'll check the image with that and see what it looks like.





(OT Whoever made that original image was foolish, that never should have been saved as a JPG. All the solid colors & sharp edges make it an ideal candidate for the PNG format, or even the GIF format.)



EDIT: I just tried the image in psp7 and in xnview. Psp7 and xnview (with high quality zoom disabled) display it the same as you xnview example. Xnview with high quality zoom enabled displays it as very soft and almost smeared. I am unable to recreate the result you got in photoshop & psp9.

[XnTriq]

Thanks for taking the time to look into this, Drahken.

It appears in your sample That xnview is applying some sort of antialiasing that psp9 isn't. Are you using a resample/high quality zoom filter in xnview but just plain zoom in psp9?

Right, I forgot to mention that High quality zoom is always turned off for both Reduce and Enlarge in my XnView installation.
As for Paint Shop Pro, there is a slider in the Display and Caching preferences:

Code: Select all

Zoom / Rescaling Quality
[ · · · · · · · · · · · · · · ●]
Faster                     Better

Adjust the Zoom / Rescaling Quality slider to set whether the Zoom tool quality is faster or better.
Faster will zoom images faster, but will display less fine detail. Better will zoom images more slowly, but display more fine detail.

I had it set to its maximum, but to my surprise I couldn't spot any difference between “fastest” and “best” (even post-restart).

After decompressing/converting test.jpeg to BMP format with each of the programs listed in my initial post, I opened Fireworks.bmp, Picture_Publisher.bmp etc. in XnView's Compare panel. The screenshot(s) were then made at a zoom level of 600%.

EDIT: I just tried the image in psp7 and in xnview. Psp7 and xnview (with high quality zoom disabled) display it the same as you xnview example. Xnview with high quality zoom enabled displays it as very soft and almost smeared. I am unable to recreate the result you got in photoshop & psp9.

<-- EDIT -- //

Paint Shop Pro prior to version 8 came with jpeglib.dll.
Versions 8+9+X+XI rely on gdiplus.dll (Microsoft Windows GDI+ Library) and jpegacc.dll for dealing with JPEGs.

• ThumbsPlus 7 & Paint Shop Photo Album 5: jpegacc.dll (AccuSoft ImageGear Imaging Toolkit)
• Animation Shop 3 & Paint Shop Pro 7: jpeglib.dll (IJG JPEG library)
• CorelDRAW Graphics Suite 11: iejpg110.flt (Corel JPEG Import/Export Filter) & ibjpg2.flt (ImageStream JPG Graphic Import Filter)

// -- EDIT -->

• Corel Support » Patches and Updates
  gdiplus.dll v5.1.30.97.0 » v5.1.3102.1360
  • Paint Shop Pro 9.00 GDI+ fix
  • Paint Shop Pro 9.01 Update
• Microsoft Download Center
  • Platform SDK Redistributable: GDI+
    gdiplus.dll v5.1.3102.1360
  • PowerPoint Viewer 2003
    gdiplus.dll v6.0.3264.0
• Los Angeles Free-Net: Fixing GDI+/JPEG Vulnerability Simplified
• Bob Powell (MSMVP): GDI+ FAQ
• Darryn Jones' Blog: GDI+ is pissing me off

[XnTriq]

I thought I had already posted what I found out in August of last year, but apparently I didn't.

• rec.photo.digital: JPEG decoding - is there only one correct solution?
• Adobe Product Newsgroups: BUG: reading JPEG files with 2x2 color subsampling
• Breeze Systems' Support Forums: Why Jpeg YUV 4:1:1?
• Nortel Photography Club Forum: Do you shoot JPEG? (colour subsampling)

Another likely contributor would be the MPEG decoder.

Actually, that's very much the likely cause. Each box has different methods for decompressing the data. On top of that, you have different reconstructive techniques like deblocking and deringing that would affect quality in varying ways. Those techniques also aren't part of the standard, so the visual quality can vary great from one decoder to the next.

Check these out for comparison: http://www.videohelp.com/images/compare.jpg

• “Mobile Visualization” Project @ Rostock University: Examples for embedding levels of detail in JPEG datastreams
• Website Optimization: Regional compression for smaller photos and images
• Macromedia Fireworks: Selectively compressing areas of an image
• Guido Vollbeding (IJG): SIGMA Photo Pro improved JPEG output – Pages #1 & #2
• Martin Brown: Probing JPEG Chroma Sampling
• Rick Matthews: Chroma Subsampling in JPG Compression
• Glenn Chan: Towards Better Chroma Subsampling
• Digital Light & Color Message Boards: Color variation due to JPEG compression
• Reduser.net Forums: Wavelet Compression Analyzed
• DataCompression.info: JPEG

Reconstruction is more accurate JPEG decompression technique. Using it results in a cleaner image.

This decompression technique is based on more accurate dequantization of JPEG DCT coefficients and unlike most other JPEG reconstruction methods is not achieved by simply smoothing of a decompressed bitmap.

Note: Reconstruction will have no effect on unchanged blocks in a final image, however it can be used to increase quality and reduce degradation in blocks that are to be re-compressed, and in operations leading to full re-compression.

XnView Forum:

• JPEG compression as lossless as possible
• Save JPG At 'Original' Quality
• What exactly does "subsampling factor" do?
• Advanced JPEG I/O

[JohnFredC]

Man! That is a wealth of useful stuff!

Thank you Mr. Librarian!

Do you know about FlowGram?

[Olivier_G]

[*]Digital Light & Color Message Boards: Color variation due to JPEG compression

I have been spotted by Mr. Librarian!

[Jaff]

Differences in display of JPEG images are usualy from decompresion method used by programs. Ex: Display by Jih-Shin Ho:
- Accurate integer
- Fast integer
- Floating point