PVRTexToolGUI: pixel errors on first 5 rows

This topic contains 3 replies, has 2 voices, and was last updated by  Tobias Hector 5 years, 11 months ago.

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  • #30680

    Texel
    Member

    I’m using a version of PVRTexToolGUI I downloaded a couple days ago. When I run the tool on an image using best quality I noticed a disproportionate number of pixel errors concentrated on the first 5 or so rows. Also the input image is a 1024×1024 Png.

    Enabled difference comparison, note the concentration of errors toward the top

    Original Image, note the blurriness toward the top:

    #35217

    Hi Texel,

    Was this image encoded with PVRTC 2bpp? If this is the case, we’ve recently found a bug with this encoder and should be pushing out a fixed version in the next day or two. If this is not PVRTC 2bpp, could you please let me know which encoding you’ve used? Also, if possible, would you be able to send us a copy of the original image?

    Regards,

    Tobias

    #35218

    Texel
    Member

    It should also be noted that the image is not intended to wrap or otherwise tile. Its a piece of a much larger image. I cut up the larger one and pvr the slices.

    Here are the settings I used:

    Here is the original image:

    #35219

    Hi Texel,

    I’ve had a look at your texture and unfortunately you seem to have hit
    upon a worst case scenario for PVRTC compression around the edges. Whilst we’ve been actively pursuing improvements in this area, the
    places where you see artifacts are very difficult to encode – PVRTC-I is a format that always assumes tiling.

    My suggestion is that you provide an “overlap” area by preserving bits of the neighbouring textures, which you use as a buffer zone for these artifacts. If you’re chopping up a larger texture anyway it makes even more sense to have this overlap as you’ll be able to achieve seamless transitions between them. I would at first try an overlap of 8 on each side, and ignore the 4 pixels nearest the edge for each texture, preserving the whole original image. Doing this should alleviate most of these problems. Hope this helps!

    Thanks,

    Tobias

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