Implementation:Ggml org Ggml Stb image write

Implementation Metadata

File Name	examples/stb_image_write.h
Repository	ggml-org/ggml
Lines	1724
Language	C
Domain Tags	Image_Processing, Third_Party, IO
Status	Active
Last Updated	2025-05-15 12:00 GMT
Knowledge Sources	ggml-org/ggml repository

Overview

examples/stb_image_write.h is a third-party single-header public domain image writing library (stb_image_write v1.16) by Sean Barrett. It is vendored as a dependency for example programs that need to save image output (e.g., SAM segmentation masks). It complements stb_image.h for complete image I/O without external library dependencies.

Description

The library provides functions to write images to files or callbacks in five formats:

• PNG -- With configurable compression level and filter mode (output is 20-50% larger than optimized implementations)
• BMP -- Simple bitmap format
• TGA -- With optional RLE compression
• JPEG -- With quality parameter
• HDR -- Radiance HDR format (float data)

Designed for simplicity over optimal file size. Uses the same single-header implementation pattern (define STB_IMAGE_WRITE_IMPLEMENTATION before including). Supports custom zlib compression (STBIW_ZLIB_COMPRESS), custom memory allocators, and Unicode filenames on Windows.

Usage

#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb_image_write.h"

// Write PNG
stbi_write_png("output.png", width, height, channels, data, stride);

// Write JPEG with quality
stbi_write_jpg("output.jpg", width, height, channels, data, quality);

Code Reference

Source Location

Repository	File	Lines
ggml-org/ggml	examples/stb_image_write.h	1724

Key Signatures

// File-based writing
int stbi_write_png(char const * filename, int w, int h, int comp, const void * data, int stride_in_bytes);
int stbi_write_bmp(char const * filename, int w, int h, int comp, const void * data);
int stbi_write_tga(char const * filename, int w, int h, int comp, const void * data);
int stbi_write_jpg(char const * filename, int w, int h, int comp, const void * data, int quality);
int stbi_write_hdr(char const * filename, int w, int h, int comp, const float * data);

// Callback-based writing
int stbi_write_png_to_func(stbi_write_func * func, void * context, int w, int h, int comp,
    const void * data, int stride_in_bytes);
int stbi_write_bmp_to_func(stbi_write_func * func, void * context, int w, int h, int comp,
    const void * data);

// Configuration
void stbi_flip_vertically_on_write(int flag);
extern int stbi_write_png_compression_level;  // default: 8
extern int stbi_write_tga_with_rle;           // default: 1

I/O Contract

Inputs

• Pixel data -- Image data as contiguous array (left-to-right, top-to-bottom)
• Dimensions -- Width, height, and component count (1-4)
• Format-specific parameters -- Stride (PNG), quality (JPEG)

Outputs

• Image file -- Written to specified path or callback
• Return value -- 0 on failure, non-zero on success

Usage Examples

Saving inference output:

#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb_image_write.h"

// Save a segmentation mask from SAM inference
unsigned char * mask = compute_segmentation_mask(model, input);
stbi_write_png("segmentation_mask.png", width, height, 1, mask, width);

// Save with callback for custom I/O
stbi_write_png_to_func(my_write_func, my_context, w, h, comp, data, stride);

Related Pages

Implements Principle

• Principle:Ggml_org_Ggml_Image_IO

Related Implementations

• Implementation:Ggml_org_Ggml_Stb_image -- Companion image reading library
• Implementation:Ggml_org_Ggml_Sam_image_preprocess -- SAM example using image I/O