Tip: Generating CSV for multi-channel histograms #275
Replies: 5 comments 3 replies
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Nice writeup! I've made a |
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I have a problem using this It gives me all zeros. |
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I'm using vips-8.6.4 in this image: https://hub.docker.com/r/felixbuenemann/vips-alpine |
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Oh I made |
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Hello @Nakilon, yes, |
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Lol I just realised I was confused by the ugly Github interface and all my comments went as top level replies but were intended to reply to your subthread. Probably not the first time I did that. |
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This discussion was originally inherited from issue #108, GitHub automatically transfers the responses as top-level. |
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Oh I see. Thank you for clarification. |
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I wanted to generate a histogram as a CSV file for single and multi-channel images. The format I needed was each row represents an intensity, each column represents a channel. This differs from the standard VIPS histogram which is a single row with a column for each intensity value for a single channel only.
My initial approach was to take the histogram and iterate over each element of the histogram which worked great on RGBA (about 4.5 seconds) but for a 2-byte greyscale image, this took about 5 minutes.
The following runs in about 0.07 seconds for RGBA and about 5 seconds for the ushort:
There may well be a better way, but that worked for me :)
Oh, the only other thing I wish I could do is add column headers but I can live without them.
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