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:

#define STB_IMAGE_IMPLEMENTATION
#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
    stbi_image_free(img);

    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.

dumpmem
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
	Flags:
		  -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:

Start debugging the program.
Place a breakpoint at a carefully select point in code, where our data is available.
Go to VSDebugPro menu and click Settings.
Specifiy a path to an image viewer that can open raw files. Click OK.
Go to VSDebugPro menu and open Console.
Dump image data with the following command:
```
dumpmem lenna.raw img w * h * c
```
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.

References

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

VSDebugPro

Inspect an image in memory

Steps to write the image to a file and load it in the viewer:

References