Inspect an image in memory

This article shows how to visualize a data buffer as an image, while debugging the program, without writing a debugging function into the program and without recompiling it.

For this purpose we will use the following simple c code:

#include "stb_image.h"

int main()
    // image width
    int w = 0;  
    // imege height
    int h = 0;
    // number of channels
    int c = 0;

    // image data
    BYTE* img = stbi_load("Lenna.png", &w, &h, &c, 0);

    // release image data

    return 0;

In order to visualize the contents of img byte buffer above, we are going to dump its contents to a file and open it with IrfanView.

Dump memory utility.
Syntax: <dumpmem> <optional flags> <filename> <address> <size>
	EX: dumpmem c:\memdump.bin 0x00656789 200
	EX: dumpmem -f c:\memdump.bin 0x00656789 200
		  -f   - Force file overwrite.
		  -a   - Append to the file.
	<filename> - output filename
	<address>  - read address, must be a hex address / pointer, can be an expression
	<size>     - size in bytes, can be an expression
Steps to write the image to a file and load it in the viewer:
  1. Start debugging the program.
  2. Place a breakpoint at a carefully select point in code, where our data is available.
  3. Go to VSDebugPro menu and click Settings.
  4. Specifiy a path to an image viewer that can open raw files. Click OK.
  5. Go to VSDebugPro menu and open Console.
  6. Dump image data with the following command:
    dumpmem lenna.raw img w * h * c
  7. Click on the file link in VSD Console to open the image in viewer.

The dumpmem utility uses the Visual Studio C++ debugger interface to automatically evaluate the address of img and the size from w * h * c expression.


HxD a free hex editor.

IrfanView freeware for non-commercial use image viewer.

Stb Image public domain image loader single file library.

Lenna png image