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mipgen: fixups / clarification regarding sRGB.

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The `g_linearized` variable was being used for two purposes: to denote
the linearity of the source format AND the linearity of the destination
format. This was confusing and is now split is `sourceIsLinear` and
`destIsLinear`.

This change has no effect on the the look of the suzanne demo.
This commit is contained in:
Philip Rideout
2022-04-11 11:04:20 -07:00
parent 6c59945395
commit df03fdf3d7
5 changed files with 59 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
libs/image/include/image/ColorTransform.h
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@@ -158,8 +158,8 @@ inline filament::math::float3 linearToSRGB(const filament::math::float3& color)
return sRGBColor;
}
// Creates a n-channel sRGB image from a linear floating-point image.
// The source image can have more than N channels, but only the first N are converted to sRGB.
// Creates a N-channel sRGB image from a linear floating-point image.
// The source image can have more than N channels, but only the first 3 are converted to sRGB.
template<typename T, int N = 3>
std::unique_ptr<uint8_t[]> fromLinearTosRGB(const LinearImage& image) {
const size_t w = image.getWidth();

33
libs/imageio/include/imageio/BlockCompression.h
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@@ -116,7 +116,7 @@ enum class AstcSemantic {
struct AstcConfig {
AstcPreset quality;
AstcSemantic semantic;
filament::math::ushort2 blocksize;
filament::math::ushort2 blocksize;
bool srgb;
};
@@ -182,6 +182,37 @@ struct CompressionConfig {
AstcConfig astc;
S3tcConfig s3tc;
EtcConfig etc;
bool isLinear() const {
if (type == ASTC) {
return !astc.srgb;
}
switch (type == S3TC ? s3tc.format : etc.format) {
case CompressedFormat::R11_EAC:
case CompressedFormat::SIGNED_R11_EAC:
case CompressedFormat::RG11_EAC:
case CompressedFormat::SIGNED_RG11_EAC:
case CompressedFormat::RGB8_ETC2:
case CompressedFormat::RGB8_ALPHA1_ETC2:
case CompressedFormat::RGBA8_ETC2_EAC:
case CompressedFormat::RGB_S3TC_DXT1:
case CompressedFormat::RGBA_S3TC_DXT1:
case CompressedFormat::RGBA_S3TC_DXT3:
case CompressedFormat::RGBA_S3TC_DXT5:
return true;
case CompressedFormat::SRGB8_ETC2:
case CompressedFormat::SRGB8_ALPHA1_ETC:
case CompressedFormat::SRGB8_ALPHA8_ETC2_EAC:
case CompressedFormat::SRGB_S3TC_DXT1:
case CompressedFormat::SRGB_ALPHA_S3TC_DXT1:
case CompressedFormat::SRGB_ALPHA_S3TC_DXT3:
case CompressedFormat::SRGB_ALPHA_S3TC_DXT5:
return false;
default:
// This should be unreachable.
assert(false && "ASTC formats are already handled");
return false;
}
}
};
bool parseOptionString(const std::string& options, CompressionConfig* config);

2
libs/imageio/src/BlockCompression.cpp
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@@ -381,7 +381,7 @@ static void extract4x4RGBA(uint8_t* dst, const LinearImage& source, uint32_t x0,
// - DXT1 with no alpha (16 input pixels in 64 bits of output, 6:1)
// - DXT5 with alpha (16 input pixels into 128 bits of output, 4:1)
//
// TODO: investigate using something more capable than STB (eg AMD Compressenator, bimg, libsquish)
// TODO: remove this in favor of basisu
CompressedTexture s3tcCompress(const LinearImage& original, S3tcConfig config) {
const bool dxt5 = config.format == CompressedFormat::RGBA_S3TC_DXT5;
LinearImage source = extendToFourChannels(original);

6
samples/CMakeLists.txt
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@@ -151,9 +151,9 @@ add_mesh("assets/models/monkey/monkey.obj" "suzanne.filamesh")
# Use a RGBA compression format for Metal and Vulkan support.
set (COMPRESSION "--compression=s3tc_rgba_dxt5")
add_ktxfiles("assets/models/monkey/albedo.png" "albedo_s3tc.ktx" "${COMPRESSION}")
add_ktxfiles("assets/models/monkey/roughness.png" "roughness.ktx" "${COMPRESSION};--grayscale")
add_ktxfiles("assets/models/monkey/metallic.png" "metallic.ktx" "${COMPRESSION};--grayscale")
add_ktxfiles("assets/models/monkey/ao.png" "ao.ktx" "${COMPRESSION};--grayscale")
add_ktxfiles("assets/models/monkey/roughness.png" "roughness.ktx" "${COMPRESSION};--grayscale;--linear")
add_ktxfiles("assets/models/monkey/metallic.png" "metallic.ktx" "${COMPRESSION};--grayscale;--linear")
add_ktxfiles("assets/models/monkey/ao.png" "ao.ktx" "${COMPRESSION};--grayscale;--linear")
add_pngfile("assets/models/monkey/normal.png" "normal.png")

31
tools/mipgen/src/main.cpp
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@@ -48,7 +48,7 @@ static bool g_addAlpha = false;
static bool g_stripAlpha = false;
static bool g_grayscale = false;
static bool g_ktxContainer = false;
static bool g_linearized = false;
static bool g_sourceIsLinear = false;
static bool g_quietMode = false;
static uint32_t g_mipLevelCount = 0;
@@ -71,13 +71,13 @@ Options:
--license, -L
print copyright and license information
--linear, -l
assume that image pixels are already linearized
specifies that the source image is linear (converts to floats without transformation)
--page, -p
generate HTML page for review purposes (mipmap.html)
--quiet, -q
suppress console output from the mipgen tool
--grayscale, -g
create a single-channel image and do not perform gamma correction
create a single-channel image
--format=[exr|hdr|rgbm|psd|png|dds|ktx], -f [exr|hdr|rgbm|psd|png|dds|ktx]
specify output file format, inferred from output pattern if omitted
--kernel=[box|nearest|hermite|gaussian|normals|mitchell|lanczos|min], -k [filter]
@@ -190,7 +190,7 @@ static int handleArguments(int argc, char* argv[]) {
license();
exit(0);
case 'l':
g_linearized = true;
g_sourceIsLinear = true;
break;
case 'g':
g_grayscale = true;
@@ -273,7 +273,7 @@ int main(int argc, char* argv[]) {
g_ktxContainer = true;
g_formatSpecified = true;
} else if (!g_formatSpecified) {
g_format = ImageEncoder::chooseFormat(outputPattern, g_linearized);
g_format = ImageEncoder::chooseFormat(outputPattern, g_sourceIsLinear);
}
if (!g_quietMode) {
@@ -282,7 +282,7 @@ int main(int argc, char* argv[]) {
ifstream inputStream(inputPath.getPath(), ios::binary);
LinearImage sourceImage = ImageDecoder::decode(inputStream, inputPath.getPath(),
g_linearized ? ImageDecoder::ColorSpace::LINEAR : ImageDecoder::ColorSpace::SRGB);
g_sourceIsLinear ? ImageDecoder::ColorSpace::LINEAR : ImageDecoder::ColorSpace::SRGB);
if (!sourceImage.isValid()) {
cerr << "Unable to open image: " << inputPath.getPath() << endl;
return 1;
@@ -337,15 +337,25 @@ int main(int argc, char* argv[]) {
.pixelDepth = 0,
};
size_t componentCount = sourceImage.getChannels();
// Try to choose an internal format that has the same transformation function as the
// source format. This varible may be adjusted later, after the destination format has
// been resolved.
bool destIsLinear = g_sourceIsLinear;
if (componentCount == 1) {
info.glFormat = info.glBaseInternalFormat = Ktx1Bundle::RED;
info.glInternalFormat = Ktx1Bundle::R8;
destIsLinear = true;
} else if (componentCount == 3) {
info.glFormat = info.glBaseInternalFormat = Ktx1Bundle::RGB;
info.glInternalFormat = Ktx1Bundle::RGB8;
info.glInternalFormat = destIsLinear ? Ktx1Bundle::RGB8 : Ktx1Bundle::SRGB8;
} else if (componentCount == 4) {
info.glFormat = info.glBaseInternalFormat = Ktx1Bundle::RGBA;
info.glInternalFormat = Ktx1Bundle::RGBA8;
info.glInternalFormat = destIsLinear ? Ktx1Bundle::RGBA8 : Ktx1Bundle::SRGB8_ALPHA8;
} else {
cerr << "Bad component count." << endl;
return 1;
}
#ifdef IMAGEIO_SUPPORTS_BLOCK_COMPRESSION
CompressionConfig config {};
@@ -359,6 +369,7 @@ int main(int argc, char* argv[]) {
// glFormat should be 0, and glBaseInternalFormat should be RED, RG, RGB, or RGBA.
// The glInternalFormat field is the only field that specifies the actual format.
info.glFormat = 0;
destIsLinear = config.isLinear();
}
#else
if (!g_compression.empty()) {
@@ -387,11 +398,11 @@ int main(int argc, char* argv[]) {
return;
}
#endif
if (g_grayscale && g_linearized) {
if (g_grayscale && destIsLinear) {
data = fromLinearToGrayscale<uint8_t>(image);
} else if (g_grayscale) {
data = fromLinearTosRGB<uint8_t, 1>(image);
} else if (g_linearized) {
} else if (destIsLinear) {
if (componentCount == 3) {
data = fromLinearToRGB<uint8_t, 3>(image);
} else {