Threshold -evaluate-sequence

[QuantumBoy]

Hi,

It's pretty obvious what most of the

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-list evaluate

options do, but I can't work out what

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threshold

actually calculates? How can you have a threshold of a sequence of images?

Thanks,
QB

[snibgo]

How can you have a threshold of a sequence of images?

Quite easily, though I never have until today.

Suppose you have two images of the same size. The output of "-evaluate-sequence threshold" is each pixel of the first image thresholded by the corresponding pixel of the second image. If you have a third image, this is used to threshold the previous result. And so on.

For example:

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convert toes.png ( +clone -blur 0x3 ) -evaluate-sequence threshold evalseq_t.png

[QuantumBoy]

Great answer - thank you! So unlike 'mean', for example, 'threshold' will be different depending upon the order that you input images?

[snibgo]

Yes. For example, swapping the these particular inputs:

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convert toes.png ( +clone -blur 0x3 ) +swap -evaluate-sequence threshold evalseq_t2.png