Skip to content

ASTC HDR 6x6 Example Images

Jump to bottom
Rich Geldreich edited this page Dec 27, 2024 · 6 revisions

This page shows a few .EXR/.PNG images compressed to .KTX2 ASTC 6x6 HDR or ASTC 6x6 HDR intermediate at various codec settings.

LDR/SDR inputs were upconverted to HDR by first converting them from sRGB to linear light RGB, then multiplying by a luminance of 100 nits (typical SDR monitors range from 80-100 nits).

For easy viewing on the web, the HDR images are tone mapped using a simple per-component global Reinhard tone mapping operator at various exposures. The tone mapped result was converted to sRGB with no dithering.

  • Original tree.exr, 928x906, Reinhard tone mapped, log2 exposure scale=1:
    image

  • ASTC 6x6 HDR intermediate, Reinhard tone mapped, log2 exposure scale=1:
    .KTX2 file size: 315,877, 3.01 bits/pixel
    Command line: basisu -lambda 3000 -hdr_6x6i_level 8 -debug_images -stats -debug C:\dev\lightprobe\Tree.exr
    image

  • ASTC 6x6 HDR intermediate, Reinhard tone mapped, log2 exposure scale=-2:
    image

  • ASTC 6x6 HDR intermediate, Reinhard tone mapped, log2 exposure scale=4:
    image

  • ASTC 6x6 HDR intermediate, Reinhard tone mapped, log2 exposure scale=6:
    image

  • BC6H, Reinhard tone mapped, log2 exposure scale=1:
    image

  • Original desk.exr, 644x874, Reinhard tone mapped:
    image

  • ASTC 6x6 HDR (3.56 bits/pixel):
    Command line: basisu -hdr_6x6_level 8 C:\dev\lightprobe\desk.exr -stats
    image

  • BC6H (8 bits/pixel):
    image

  • Original BarHarborSunrise.exr, resampled to 3216x1809, Reinhard tone mapped:
    image

  • ASTC 6x6 HDR (3.56 bits/pixel):
    Command line: basisu -hdr_6x6_level 8 C:\dev\lightprobe\BarHarborSunrise.exr -resample_factor .75 -stats -debug_images
    image

  • BC6H (8 bits/pixel)
    image

  • Original CandleGlass.exr, 1000x810, Reinhard tone mapped, log2 exposure scale=2:
    image

  • ASTC 6x6 HDR (3.56 bits/pixel), log2 exposure scale=2:
    Command line: basisu -hdr_6x6_level 8 C:\dev\lightprobe\CandleGlass.exr -stats -debug_images
    image

  • BC6H (8 bits/pixel), log2 exposure scale=2:
    image

  • ASTC 6x6 HDR (3.56 bits/pixel), log2 exposure scale=-8: image

  • ASTC 6x6 HDR (3.56 bits/pixel), log2 exposure scale=8:
    image

  • Original .PNG, 2000x1334: image

  • Upconverted to linear light (100 nits), compressed to ASTC 6x6 intermediate .KTX2, uncompressed to ASTC 6x6 HDR, decoded and converted back to sRGB:
    .KTX2 file size: 697,456 bytes, 2.09 bits/pixel
    Command line: basisu -lambda 5000 -hdr_6x6i_level 5 C:\dev\test_images\cnn-election-night3.png
    image

  • BC6H:
    image

  • Original starwars_768.png, 768x768:
    image

  • Upconverted to linear light (100 nits), compressed to ASTC 6x6 intermediate .KTX2, uncompressed to ASTC 6x6 HDR, decoded and converted back to sRGB:
    .KTX2 file size: 191,228 bytes, 2.59 bits/pixel
    Command line: basisu -lambda 5000 -hdr_6x6i_level 1 -debug_images -stats C:\dev\test_images\starwars_768.png image

  • BC6H:
    image

  • Original chief_768.png, 768x384:
    image

  • Upconverted to linear light (100 nits), compressed to ASTC 6x6 intermediate .KTX2, uncompressed to ASTC 6x6 HDR, decoded and converted back to sRGB:
    .KTX2 file size: 102,657 bytes, 2.78 bits/pixel
    Command line: basisu -lambda 5000 -hdr_6x6i_level 5 -debug_images -stats C:\dev\test_images\chief_768.png -debug
    image

  • BC6H (8 bits/pixel):
    image

  • ASTC 6x6 HDR intermediate:
    .KTX2 file size: 87,930 bytes, 2.39 bits/pixel
    Command line: basisu -lambda 20000 -hdr_6x6i_level 5 -debug_images -stats C:\dev\test_images\chief_768.png -debug
    image

  • ASTC 6x6 HDR intermediate:
    .KTX2 file size: 68,217 bytes, 1.85 bits/pixel
    image

  • ASTC 6x6 HDR intermediate:
    .KTX2 file size: 64,677 bytes, 1.75 bits/pixel
    image

  • Original rain_1k.png, 1024x685
    image

  • Upconverted to linear light (100 nits), compressed to ASTC 6x6 .KTX2, uncompressed to ASTC 6x6 HDR, decoded and converted back to sRGB:
    Command line: basisu -hdr_6x6_level 8 -debug_images -stats -debug C:\dev\test_images\rain_1k.png
    image

  • BC6H (8 bits/pixel)
    image

  • ASTC 6x6 HDR intermediate
    .KTX2 file size: 228,856 bytes, 2.61 bits/pixel
    Command line: basisu -lambda 10000 -hdr_6x6i_level 8 -debug_images -stats -debug C:\dev\test_images\rain_1k.png
    image

  • ASTC 6x6 HDR intermediate
    .KTX2 file size: 200,972 bytes, 2.29 bits/pixel
    Command line: basisu -lambda 30000 -hdr_6x6i_level 8 -debug_images -stats -debug C:\dev\test_images\rain_1k.png
    image

  • Original tng.png, 700x999
    image

  • ASTC HDR 6x6 (3.56 bits/pixel)
    .KTX2 file size: 299,392 3.43 bits/pixel
    Command line: basisu -hdr_6x6_level 8 -debug_images -stats -debug C:\dev\test_images\tng.png
    image

  • BC6H (8 bits/pixel)
    image

Clone this wiki locally