What is the dot-product of two images?

[StridingDragon]

While looking through the ESP32 DSP documentation (https://docs.espressif.com/projects/esp ... marks.html) I stumbled across functions that reportedly create the "dotproduct of two images"—no other information is provided.

I have never heard of a dot-product of two images in all my years of graphics programming—but it may be a signal processing-specific expression. I have trouble wrapping my head around the term because images are 2D arrays of pixels and the dot-product is a vector operation. I just don't see how the two things are in any way related or what result the operation would yield.

Can anyone tell me what the dot-product of two images is and what it is used for?

[Craige Hales]

https://github.com/espressif/esp-dsp/bl ... _dotprod.h
is the only info I found. It might be the sum of the pixel-by-pixel product.
If the image pixels are signed, between -1 and 1, the result might be a correlation between the images...negative total if most pixels had opposite sign values, positive total if most had same sign values.
I'm guessing. Never seen it before either.

[StridingDragon]

Too bad no one seems to have an answer for this. I can see the implementation of it (https://github.com/espressif/esp-dsp/tr ... es/dotprod) and all it does is multiply pixels with each other and summing the products up as the return value. Not sure for what purpose this operation could be useful.

[tommeyers]

Investigate SVD

http://blog.kleinproject.org/?p=588

Please tell us what you think.

Tom

[StridingDragon]

Interesting. Thanks, Tom. This is exciting stuff. I had not heard of SVD before, but it sounds really impressive.