pvrtextool compression artifact?

This topic contains 1 reply, has 2 voices, and was last updated by  Joe Davis 3 years, 3 months ago.

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  • #31777

    punto
    Member

    Hi.

    I’m running pvrtextool to compress a texture to use as a 2d sprite on iOS. My original image is square, 56×56 pixels, and I repeated the borders by 4 pixels to avoid the wrap around from the repeat, so ends up as 64×64. I’m running this version on linux:

    PVRTexToolCL version 3.4
    SDK Version: 3.3@2825756
    PVRTexLib 4.13 | JpegLib version 6b | LibPNG version 1.5.12

    with the following options:

    pvrtextool -i /tmp/image.png -o /tmp/image.pvr -f PVRTC1_4 -m 0 -legacypvr

    My problem is that it’s creating some artifacts in the corners, as shown here (zoomed in our our PC renderer using opengl, original on the right, compressed version on the left):

    http://imgur.com/SulxYbf

    The black corners on the original are all black pixels, completely transparent (so 0, 0, 0, 0, 4×4 pixels), but on the compressed image they seem to get polluted by adjacent pixels, which is causing some artifacts on the corners when I show the inner square as a sprite. I also tried to fill those corners with the pixels on the corner of the original image (so the top left corner filled with the pixel on 0,0 of the original), but I had similar artifacts.

    Is there a way to avoid this, or just to use pvr compressed images as sprites in general?

    Thanks!

    #38904

    Joe Davis
    Member

    Hi,

    When you’ve reproduced the artefacts in your OpenGL PC render, how is the image decompressed? Do the artefacts occur when the image is viewed in PVRTexToolGUI?

    Thanks,
    Joe

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