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[rtextures] Created ImageFromChannel() (#4105)
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* created ImageFromChannel

Adds the possibility to extract a specific channel from an image

* naming convention

* example window height

* removed threshold

* removed alpha channel

* channel example organization

* updated channel example image
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@brccabral
brccabral authored Jun 30, 2024
1 parent 5b8efd6 commit 6e2661f
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106 changes: 106 additions & 0 deletions examples/textures/textures_image_channel.c
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/*******************************************************************************************
*
* raylib [textures] example - Retrive image channel (mask)
*
* NOTE: Images are loaded in CPU memory (RAM); textures are loaded in GPU memory (VRAM)
*
* Example originally created with raylib 5.1-dev, last time updated with raylib 5.1-dev
*
* Example contributed by Bruno Cabral (github.com/brccabral) and reviewed by Ramon Santamaria (@raysan5)
*
* Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
* BSD-like license that allows static linking with closed source software
*
* Copyright (c) 2024-2024 Bruno Cabral (github.com/brccabral) and Ramon Santamaria (@raysan5)
*
********************************************************************************************/

#include <raylib.h>

//------------------------------------------------------------------------------------
// Program main entry point
//------------------------------------------------------------------------------------
int main(void)
{
// Initialization
//--------------------------------------------------------------------------------------

const int screenWidth = 800;
const int screenHeight = 450;

InitWindow(screenWidth, screenHeight, "raylib [textures] example - extract channel from image");

Image fudesumiImage = LoadImage("resources/fudesumi.png");

Image imageAlpha = ImageFromChannel(fudesumiImage, 3);
ImageAlphaMask(&imageAlpha, imageAlpha);

Image imageRed = ImageFromChannel(fudesumiImage, 0);
ImageAlphaMask(&imageRed, imageAlpha);

Image imageGreen = ImageFromChannel(fudesumiImage, 1);
ImageAlphaMask(&imageGreen, imageAlpha);

Image imageBlue = ImageFromChannel(fudesumiImage, 2);
ImageAlphaMask(&imageBlue, imageAlpha);

Image backgroundImage = GenImageChecked(screenWidth, screenHeight, screenWidth/20, screenHeight/20, ORANGE, YELLOW);

Texture2D fudesumiTexture = LoadTextureFromImage(fudesumiImage);
Texture2D textureAlpha = LoadTextureFromImage(imageAlpha);
Texture2D textureRed = LoadTextureFromImage(imageRed);
Texture2D textureGreen = LoadTextureFromImage(imageGreen);
Texture2D textureBlue = LoadTextureFromImage(imageBlue);
Texture2D backgroundTexture = LoadTextureFromImage(backgroundImage);

UnloadImage(fudesumiImage);
UnloadImage(imageAlpha);
UnloadImage(imageRed);
UnloadImage(imageGreen);
UnloadImage(imageBlue);
UnloadImage(backgroundImage);

SetTargetFPS(60); // Set our game to run at 60 frames-per-second

Rectangle fudesumiRec = {0, 0, fudesumiImage.width, fudesumiImage.height};

Rectangle fudesumiPos = {50, 10, fudesumiImage.width*0.8f, fudesumiImage.height*0.8f};
Rectangle redPos = { 410, 10, fudesumiPos.width / 2, fudesumiPos.height / 2 };
Rectangle greenPos = { 600, 10, fudesumiPos.width / 2, fudesumiPos.height / 2 };
Rectangle bluePos = { 410, 230, fudesumiPos.width / 2, fudesumiPos.height / 2 };
Rectangle alphaPos = { 600, 230, fudesumiPos.width / 2, fudesumiPos.height / 2 };

//--------------------------------------------------------------------------------------

// Main game loop
while (!WindowShouldClose()) // Detect window close button or ESC key
{
// Draw
//----------------------------------------------------------------------------------
BeginDrawing();

DrawTexture(backgroundTexture, 0, 0, WHITE);
DrawTexturePro(fudesumiTexture, fudesumiRec, fudesumiPos, (Vector2) {0, 0}, 0, WHITE);

DrawTexturePro(textureRed, fudesumiRec, redPos, (Vector2) {0, 0}, 0, RED);
DrawTexturePro(textureGreen, fudesumiRec, greenPos, (Vector2) {0, 0}, 0, GREEN);
DrawTexturePro(textureBlue, fudesumiRec, bluePos, (Vector2) {0, 0}, 0, BLUE);
DrawTexturePro(textureAlpha, fudesumiRec, alphaPos, (Vector2) {0, 0}, 0, WHITE);

EndDrawing();
//----------------------------------------------------------------------------------
}

// De-Initialization
//--------------------------------------------------------------------------------------
UnloadTexture(backgroundTexture);
UnloadTexture(fudesumiTexture);
UnloadTexture(textureRed);
UnloadTexture(textureGreen);
UnloadTexture(textureBlue);
UnloadTexture(textureAlpha);
CloseWindow(); // Close window and OpenGL context
//--------------------------------------------------------------------------------------

return 0;
}
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1 change: 1 addition & 0 deletions src/raylib.h
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Expand Up @@ -1334,6 +1334,7 @@ RLAPI Image ImageCopy(Image image);
RLAPI Image ImageFromImage(Image image, Rectangle rec); // Create an image from another image piece
RLAPI Image ImageText(const char *text, int fontSize, Color color); // Create an image from text (default font)
RLAPI Image ImageTextEx(Font font, const char *text, float fontSize, float spacing, Color tint); // Create an image from text (custom sprite font)
RLAPI Image ImageFromChannel(Image image, int selectedChannel); // Create an image from a selected channel of another image
RLAPI void ImageFormat(Image *image, int newFormat); // Convert image data to desired format
RLAPI void ImageToPOT(Image *image, Color fill); // Convert image to POT (power-of-two)
RLAPI void ImageCrop(Image *image, Rectangle crop); // Crop an image to a defined rectangle
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202 changes: 202 additions & 0 deletions src/rtextures.c
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Expand Up @@ -1630,6 +1630,208 @@ Image ImageTextEx(Font font, const char *text, float fontSize, float spacing, Co
return imText;
}

// Create an image from a selected channel of another image
Image ImageFromChannel(Image image, int selectedChannel)
{
Image result = { 0 };

// Security check to avoid program crash
if ((image.data == NULL) || (image.width == 0) || (image.height == 0))
return result;

// Check selected channel
if (selectedChannel < 0)
{
TRACELOG(LOG_WARNING, "Channel cannot be negative. Setting channel to 0.");
selectedChannel = 0;
}
if (image.format == PIXELFORMAT_UNCOMPRESSED_GRAYSCALE
|| image.format == PIXELFORMAT_UNCOMPRESSED_R32
|| image.format == PIXELFORMAT_UNCOMPRESSED_R16
)
{
if (selectedChannel > 0)
{
TRACELOG(LOG_WARNING, "This image has only 1 channel. Setting channel to it.");
selectedChannel = 0;
}
}
else if (image.format == PIXELFORMAT_UNCOMPRESSED_GRAY_ALPHA)
{
if (selectedChannel > 1)
{
TRACELOG(LOG_WARNING, "This image has only 2 channels. Setting channel to alpha.");
selectedChannel = 1;
}
}
else if (image.format == PIXELFORMAT_UNCOMPRESSED_R5G6B5
|| image.format == PIXELFORMAT_UNCOMPRESSED_R8G8B8
|| image.format == PIXELFORMAT_UNCOMPRESSED_R32G32B32
|| image.format == PIXELFORMAT_UNCOMPRESSED_R16G16B16
)
{
if (selectedChannel > 2)
{
TRACELOG(LOG_WARNING, "This image has only 3 channels. Setting channel to red.");
selectedChannel = 0;
}
}

// formats rgba
if (selectedChannel > 3)
{
TRACELOG(LOG_WARNING, "ImageFromChannel supports channels 0 to 3 (rgba). Setting channel to alpha.");
selectedChannel = 3;
}

result.format = PIXELFORMAT_UNCOMPRESSED_GRAYSCALE;
result.height = image.height;
result.width = image.width;
result.mipmaps = 1;

unsigned char *pixels = (unsigned char *)RL_CALLOC(image.width * 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 * image.height; ++i)
{
float imageValue = -1;
switch (image.format)
{
case PIXELFORMAT_UNCOMPRESSED_GRAYSCALE:
{
imageValue = (float)((unsigned char *)image.data)[i + selectedChannel]/255.0f;

} break;
case PIXELFORMAT_UNCOMPRESSED_GRAY_ALPHA:
{
imageValue = (float)((unsigned char *)image.data)[k + selectedChannel]/255.0f;

k += 2;
} break;
case PIXELFORMAT_UNCOMPRESSED_R5G5B5A1:
{
unsigned short pixel = ((unsigned short *)image.data)[i];

if (selectedChannel == 0)
{
imageValue = (float)((pixel & 0b1111100000000000) >> 11)*(1.0f/31);
}
else if (selectedChannel == 1)
{
imageValue = (float)((pixel & 0b0000011111000000) >> 6)*(1.0f/31);
}
else if (selectedChannel == 2)
{
imageValue = (float)((pixel & 0b0000000000111110) >> 1)*(1.0f/31);
}
else if (selectedChannel == 3)
{
imageValue = ((pixel & 0b0000000000000001) == 0)? 0.0f : 1.0f;
}

} break;
case PIXELFORMAT_UNCOMPRESSED_R5G6B5:
{
unsigned short pixel = ((unsigned short *)image.data)[i];

if (selectedChannel == 0)
{
imageValue = (float)((pixel & 0b1111100000000000) >> 11)*(1.0f/31);
}
else if (selectedChannel == 1)
{
imageValue = (float)((pixel & 0b0000011111100000) >> 5)*(1.0f/63);
}
else if (selectedChannel == 2)
{
imageValue = (float)(pixel & 0b0000000000011111)*(1.0f/31);
}

} break;
case PIXELFORMAT_UNCOMPRESSED_R4G4B4A4:
{
unsigned short pixel = ((unsigned short *)image.data)[i];

if (selectedChannel == 0)
{
imageValue = (float)((pixel & 0b1111000000000000) >> 12)*(1.0f/15);
}
else if (selectedChannel == 1)
{
imageValue = (float)((pixel & 0b0000111100000000) >> 8)*(1.0f/15);
}
else if (selectedChannel == 2)
{
imageValue = (float)((pixel & 0b0000000011110000) >> 4)*(1.0f/15);
}
else if (selectedChannel == 3)
{
imageValue = (float)(pixel & 0b0000000000001111)*(1.0f/15);
}

} break;
case PIXELFORMAT_UNCOMPRESSED_R8G8B8A8:
{
imageValue = (float)((unsigned char *)image.data)[k + selectedChannel]/255.0f;

k += 4;
} break;
case PIXELFORMAT_UNCOMPRESSED_R8G8B8:
{
imageValue = (float)((unsigned char *)image.data)[k + selectedChannel]/255.0f;

k += 3;
} break;
case PIXELFORMAT_UNCOMPRESSED_R32:
{
imageValue = ((float *)image.data)[k];

k += 1;
} break;
case PIXELFORMAT_UNCOMPRESSED_R32G32B32:
{
imageValue = ((float *)image.data)[k + selectedChannel];

k += 3;
} break;
case PIXELFORMAT_UNCOMPRESSED_R32G32B32A32:
{
imageValue = ((float *)image.data)[k + selectedChannel];

k += 4;
} break;
case PIXELFORMAT_UNCOMPRESSED_R16:
{
imageValue = HalfToFloat(((unsigned short *)image.data)[k]);

k += 1;
} break;
case PIXELFORMAT_UNCOMPRESSED_R16G16B16:
{
imageValue = HalfToFloat(((unsigned short *)image.data)[k+selectedChannel]);

k += 3;
} break;
case PIXELFORMAT_UNCOMPRESSED_R16G16B16A16:
{
imageValue = HalfToFloat(((unsigned short *)image.data)[k + selectedChannel]);

k += 4;
} break;
default: break;
}

pixels[i] = imageValue * 255;
}
}

result.data = pixels;

return result;
}

// Resize and image to new size using Nearest-Neighbor scaling algorithm
void ImageResizeNN(Image *image,int newWidth,int newHeight)
{
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