Faint grid overlayed on high quality downsampled view

[captaincavern]

I've only noticed this since I connect my monitor through DVI, I guess the minute amount of ghosting it suffered when using VGA connection was masking it.

It's very annoying when viewing line art drawings as it's most visible for me on full white.

Could this be fixed? Thanks in advance.

Edit: it's not noticeable on photos and the best way to "see" it if you don't see it is to make a screenshot of a downsampled view of a fully white image. After opening the screenshot and cropping the client area, counting colors reveals there are two colors instead of one as it should be. Using mehdi's plugin Local equalization on that screenshot will amplify local contrast and make this grid obvious. Grid density depends apparently on zoom level.

[XnTriq]

Still having this problem, can something be done about it?

XnView Classic or MP or both, Cap'n?

[captaincavern]

Still having this problem, can something be done about it?

XnView Classic or MP or both, Cap'n?

Classic, I wouldn't know about MP as I don't use it. And of course this for both issues/topics, this one and the one you've quoted me from.

[XnTriq]

Oops, I quoted the wrong post

Anyhow — I was asking because this is an issue which has been reported for MP but not for Classic:

• v.0.21(L) Visual artifact at different zoom
• MP 0.26.1 Win: 2 issues with the GFL colour image
• MP0.26- FullScreenMode
• XnView 0.35 bad rescalling?
• MP 0.38.3 Win: PNG preview problem
• 0.48 Beta: Still graphic glitches when zooming
• 0.51: zoom out of large gif image
• 0.51 winxp,win7: Lines in pictures
• 0.51 ReSampling method error & bad resampling quality
• Bug: Scaling error
• 0.53 Win: Display errors still present
• A subtle bug about image displayed on XnView MP 0.53
• Drawing engine shows tiles on big images
• Discontinuities when downscaling large images
• v0.72: Wrong 2x zoom rendering
• Grid lines appearing with Alpha on TGAs

Could you please post a screenshot and a sample file?

[captaincavern]

No need for uploading a sample as any image will do. Here are however the grids showing up when seeing a 100% white image at a couple of different zooms:

Viewed at 77%:


Viewed at 61%:


This is not what it actually looks like of course, I've maximized the contrast as to illustrate those grids, what shows as black above (0,0,0) is actually only 254,254,254.

There should be no such grids at all, all pixels should be white.

[XnTriq]

Bug confirmed

[XnTriq]

Steps to reproduce:

1. Tools » Options... » View » View
   • Zoom step: [ Default ]
   • High quality zoom: [×] Reduce
2. Capture the entire screen (Print Screen).
3. Edit » Import Clipboard
4. Edit » Background colour...: R255/G255/B255
5. Edit » Select All
6. Edit » Clear
7. View » Zoom: 30%
8. Capture the entire screen (Print Screen).
9. Edit » Import Clipboard
10. Select the white area in the imported screenshot.
11. Edit » Crop
12. Image » Map » Normalize