A Rust program to compare two images

语言｜Language

简体中文 | Chinglish

Usage:

imgmatch <image1> <image2>

The program will try to resize the two images to the same size, then run pixel color difference summing, and print out a value.

• If the value is greater than 0.01, the two images could be considered as different images.
• If the value is less than or equal to 0.01, the two images could be considered as identical images.
• The program itself doesn't judge the images; you should use your images to test if a good threshold is 0.01.

The algorithm

See the pseudo code here:

for y in 0..MATCH_SIZE { // This line runs in parallel
	for x in 0..MATCH_SIZE {
		let p1 = img1.get_pixel(x, y);
		let p2 = img2.get_pixel(x, y);
		sr += ((p1.r as f32 / 255.0) - (p2.r as f32 / 255.0)).abs() as f32;
		sg += ((p1.g as f32 / 255.0) - (p2.g as f32 / 255.0)).abs() as f32;
		sb += ((p1.b as f32 / 255.0) - (p2.b as f32 / 255.0)).abs() as f32;
	}
}
let error = ((sr + sg + sb) / (MATCH_SIZE * MATCH_SIZE * 3) as f32).max(0.0);
println!("{error:.3}");

Supported formats:

• PNG
• JPEG, loads 4x faster than normal
• GIF
• WEBP
• PNM
• TIFF
• TGA
• DDS
• BMP
• ICO
• HDR
• OpenEXR
• Farbfeld
• AVIF
• QOI
• PCX

Deployment

First is to install Rust.

• On Non-NUMA systems, just run cargo build --release in the project directory to get the binary program, and use the program as this document says.
• On NUMA systems, compile with the feature numa enabled by running cargo build --release --features numa to get the binary program that's NUMA-specific.

Profiling

• Compile with the feature profiling, then the time consumption of each step, including image loading, resizing, and the image difference summing, will be displayed via stderr.

Test results for a reference

test1.png - test1.png = 0.000
test1.png - test2.JPG = 0.004
test1.png - test3.jpg = 0.401
test1.png - test4.png = 0.720
test1.png - test5.png = 0.402
test2.JPG - test1.png = 0.004
test2.JPG - test2.JPG = 0.000
test2.JPG - test3.jpg = 0.401
test2.JPG - test4.png = 0.720
test2.JPG - test5.png = 0.402
test3.jpg - test1.png = 0.401
test3.jpg - test2.JPG = 0.401
test3.jpg - test3.jpg = 0.000
test3.jpg - test4.png = 0.464
test3.jpg - test5.png = 0.007
test4.png - test1.png = 0.720
test4.png - test2.JPG = 0.720
test4.png - test3.jpg = 0.464
test4.png - test4.png = 0.000
test4.png - test5.png = 0.463
test5.png - test1.png = 0.402
test5.png - test2.JPG = 0.402
test5.png - test3.jpg = 0.007
test5.png - test4.png = 0.463
test5.png - test5.png = 0.000