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created ImageFromChannel

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Adds the possibility to extract a specific channel from an image
This commit is contained in:
Bruno Cabral 2024-06-25 13:26:52 -07:00
commit 0576b47320
1 changed files with 335 additions and 0 deletions
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235
src/rtextures.c
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@ -1630,6 +1630,241 @@ Image ImageTextEx(Font font, const char *text, float fontSize, float spacing, Co
return imText;
}
Image ImageFromChannel(Image image, int selected_channel, float threshold)
{
Image result = { 0 };
// Security check to avoid program crash
if ((image.data == NULL) || (image.width == 0) || (image.height == 0))
return result;
// Check thresholds limits
if (threshold < 0.0f)
{
TRACELOG(LOG_WARNING, "Threshold is from 0 to 1, changing to 0.");
threshold = 0.0f;
}
if (threshold > 1.0f)
{
TRACELOG(LOG_WARNING, "Threshold is from 0 to 1, changing to 1.");
threshold = 1.0f;
}
// Check selected channel
if (image.format == PIXELFORMAT_UNCOMPRESSED_GRAYSCALE
|| image.format == PIXELFORMAT_UNCOMPRESSED_R32
|| image.format == PIXELFORMAT_UNCOMPRESSED_R16
)
{
if (selected_channel > 0)
{
TRACELOG(LOG_WARNING, "This image has only 1 channel. Setting channel to it.");
selected_channel = 0;
}
}
else if (image.format == PIXELFORMAT_UNCOMPRESSED_GRAY_ALPHA)
{
if (selected_channel > 1)
{
TRACELOG(LOG_WARNING, "This image has only 2 channels. Setting channel to alpha.");
selected_channel = 1;
}
}
else if (image.format == PIXELFORMAT_UNCOMPRESSED_R5G6B5
|| image.format == PIXELFORMAT_UNCOMPRESSED_R8G8B8
|| image.format == PIXELFORMAT_UNCOMPRESSED_R32G32B32
|| image.format == PIXELFORMAT_UNCOMPRESSED_R16G16B16
)
{
if (selected_channel > 2)
{
TRACELOG(LOG_WARNING, "This image has only 3 channels. Setting channel to red.");
selected_channel = 0;
}
}
// formats rgba
if (selected_channel > 3 || selected_channel < 0)
{
TRACELOG(LOG_WARNING, "ImageFromChannel supports channels 0 to 3 (rgba). Setting channel to alpha.");
selected_channel = 3;
}
result.format = PIXELFORMAT_UNCOMPRESSED_GRAY_ALPHA;
result.height = image.height;
result.width = image.width;
result.mipmaps = 1;
unsigned char *pixels = (unsigned char *)RL_CALLOC(image.width * 2 * image.height, sizeof(unsigned char)); // values 0 to 255
if (image.format >= PIXELFORMAT_COMPRESSED_DXT1_RGB) TRACELOG(LOG_WARNING, "IMAGE: Pixel data retrieval not supported for compressed image formats");
else
{
for (int i = 0, k = 0; i < image.width*2*image.height; i+=2)
{
float image_value = -1;
float image_alpha = 0;
switch (image.format)
{
case PIXELFORMAT_UNCOMPRESSED_GRAYSCALE:
{
image_value = (float)((unsigned char *)image.data)[i + selected_channel]/255.0f;
image_alpha = 1;
} break;
case PIXELFORMAT_UNCOMPRESSED_GRAY_ALPHA:
{
image_value = (float)((unsigned char *)image.data)[k + selected_channel]/255.0f;
image_alpha = (float)((unsigned char *)image.data)[k + 1]/255.0f;
k += 2;
} break;
case PIXELFORMAT_UNCOMPRESSED_R5G5B5A1:
{
unsigned short pixel = ((unsigned short *)image.data)[i];
if (selected_channel == 0)
{
image_value = (float)((pixel & 0b1111100000000000) >> 11)*(1.0f/31);
}
else if (selected_channel == 1)
{
image_value = (float)((pixel & 0b0000011111000000) >> 6)*(1.0f/31);
}
else if (selected_channel == 2)
{
image_value = (float)((pixel & 0b0000000000111110) >> 1)*(1.0f/31);
}
else if (selected_channel == 3)
{
image_value = ((pixel & 0b0000000000000001) == 0)? 0.0f : 1.0f;
}
image_alpha = ((pixel & 0b0000000000000001) == 0)? 0.0f : 1.0f;
} break;
case PIXELFORMAT_UNCOMPRESSED_R5G6B5:
{
unsigned short pixel = ((unsigned short *)image.data)[i];
if (selected_channel == 0)
{
image_value = (float)((pixel & 0b1111100000000000) >> 11)*(1.0f/31);
}
else if (selected_channel == 1)
{
image_value = (float)((pixel & 0b0000011111100000) >> 5)*(1.0f/63);
}
else if (selected_channel == 2)
{
image_value = (float)(pixel & 0b0000000000011111)*(1.0f/31);
}
image_alpha = 1;
} break;
case PIXELFORMAT_UNCOMPRESSED_R4G4B4A4:
{
unsigned short pixel = ((unsigned short *)image.data)[i];
if (selected_channel == 0)
{
image_value = (float)((pixel & 0b1111000000000000) >> 12)*(1.0f/15);
}
else if (selected_channel == 1)
{
image_value = (float)((pixel & 0b0000111100000000) >> 8)*(1.0f/15);
}
else if (selected_channel == 2)
{
image_value = (float)((pixel & 0b0000000011110000) >> 4)*(1.0f/15);
}
else if (selected_channel == 3)
{
image_value = (float)(pixel & 0b0000000000001111)*(1.0f/15);
}
image_alpha = (float)(pixel & 0b0000000000001111)*(1.0f/15);
} break;
case PIXELFORMAT_UNCOMPRESSED_R8G8B8A8:
{
image_value = (float)((unsigned char *)image.data)[k + selected_channel]/255.0f;
image_alpha = (float)((unsigned char *)image.data)[k + 3]/255.0f;
k += 4;
} break;
case PIXELFORMAT_UNCOMPRESSED_R8G8B8:
{
image_value = (float)((unsigned char *)image.data)[k + selected_channel]/255.0f;
image_alpha = 1;
k += 3;
} break;
case PIXELFORMAT_UNCOMPRESSED_R32:
{
image_value = ((float *)image.data)[k];
image_alpha = 1;
k += 1;
} break;
case PIXELFORMAT_UNCOMPRESSED_R32G32B32:
{
image_value = ((float *)image.data)[k + selected_channel];
image_alpha = 1;
k += 3;
} break;
case PIXELFORMAT_UNCOMPRESSED_R32G32B32A32:
{
image_value = ((float *)image.data)[k + selected_channel];
image_alpha = ((float *)image.data)[k + 3];
k += 4;
} break;
case PIXELFORMAT_UNCOMPRESSED_R16:
{
image_value = HalfToFloat(((unsigned short *)image.data)[k]);
image_alpha = 1;
k += 1;
} break;
case PIXELFORMAT_UNCOMPRESSED_R16G16B16:
{
image_value = HalfToFloat(((unsigned short *)image.data)[k+selected_channel]);
image_alpha = 1;
k += 3;
} break;
case PIXELFORMAT_UNCOMPRESSED_R16G16B16A16:
{
image_value = HalfToFloat(((unsigned short *)image.data)[k + selected_channel]);
image_alpha = HalfToFloat(((unsigned short *)image.data)[k + 3]);
k += 4;
} break;
default: break;
}
// verify threshold
unsigned char result_value = 0;
unsigned char result_alpha = 0;
if (image_value >= threshold)
{
result_value = image_value * 255;
if (image_alpha)
{
result_alpha = 255;
}
}
pixels[i] = result_value;
pixels[i + 1] = result_alpha;
}
}
result.data = pixels;
return result;
}
// Resize and image to new size using Nearest-Neighbor scaling algorithm
void ImageResizeNN(Image *image,int newWidth,int newHeight)
{