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Fast dark picture subtraction

Hi,
I'm searching for a fast way to substract a dark image from another image.
If the dark image pixel value is greater than the corresponding image pixel, the resulting image pixel should be zero. Otherwise, it should be simply substracted.

Are there special functions for doing this job?

I got an AT91SAM9260 processor and the image data is 10bit depth, laying in a 16-bit array.

Many thank,
Stefan

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  • The v5 example already processes two samples per iteration. I don't believe that the loop would benefit much from increasing that number.

    Probably not on an ARM9, where only the loop overhead would be smaller (LDR takes 1 cycles on ARM9 and LDM takes n cycles, so there's no reduction in cycle count by using LDM. I was thinking of ARM7, where LDR takes 3 cycles and LDM takes n+2 cycles, and the cycle count reduction by using the load-multiple instructions can be significant).

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  • The v5 example already processes two samples per iteration. I don't believe that the loop would benefit much from increasing that number.

    Probably not on an ARM9, where only the loop overhead would be smaller (LDR takes 1 cycles on ARM9 and LDM takes n cycles, so there's no reduction in cycle count by using LDM. I was thinking of ARM7, where LDR takes 3 cycles and LDM takes n+2 cycles, and the cycle count reduction by using the load-multiple instructions can be significant).

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