Blp Uncompressed is bgra, not rgba
Posted: Thu Sep 09, 2021 3:57 pm
XnView: MP 0.98.4 - 64 bit
OS: Windows - 64bit
XnViewMP load BLP pictures with the wrong colors
Effect: just getting wrong picture colors
To reproduce:
1. Download original blp file from: https://wow.tools/casc/file/chash?conte ... les915.blp
2. This is how the image should look https://wow.tools/casc/preview/chash?bu ... 04dd466d8f
3. XnViewMP show up wrong colors when u open blp file.
I have attached how the image looks when u open that blp in XNViewMP
Expected colors:
Solution:
The header of blp
if preferredFormat is 8 and colorEncoding is 3, the data is in BGRA format and it needs flipping to RGBA
For example:
OS: Windows - 64bit
XnViewMP load BLP pictures with the wrong colors
Effect: just getting wrong picture colors
To reproduce:
1. Download original blp file from: https://wow.tools/casc/file/chash?conte ... les915.blp
2. This is how the image should look https://wow.tools/casc/preview/chash?bu ... 04dd466d8f
3. XnViewMP show up wrong colors when u open blp file.
I have attached how the image looks when u open that blp in XNViewMP
The header of blp
Code: Select all
struct BlpFile{
uint32_t fileIdent;
int32_t version;
uint8_t colorEncoding;
uint8_t alphaChannelBitDepth;
uint8_t preferredFormat;
uint8_t mipmap_level_and_flags;
int32_t width;
int32_t height;
int32_t offsets[16];
int32_t lengths[16];
uint8_t palette[1024];
};For example:
Code: Select all
if (blpFile->colorEncoding == 3) {
//Turn BGRA into RGBA
validSize = 4 * width * height;
mipmapStruct.texture = std::vector<uint8_t>(validSize, 0);
for (int j = 0; j < width * height; j++) {
uint8_t b = data[j * 4 + 0];
uint8_t g = data[j * 4 + 1];
uint8_t r = data[j * 4 + 2];
uint8_t a = data[j * 4 + 3];
mipmapStruct.texture[j * 4 + 0] = r;
mipmapStruct.texture[j * 4 + 1] = g;
mipmapStruct.texture[j * 4 + 2] = b;
mipmapStruct.texture[j * 4 + 3] = a;
}
}
Thanks to your detailed description I can reproduce 