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27 lines
970 B
Plaintext
27 lines
970 B
Plaintext
---
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syntax: markdown
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tags: [tldr, common]
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source: https://github.com/tldr-pages/tldr.git
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---
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# pnmnorm
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> Normalize the contrast in a PNM image.
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> See also: `pnmhisteq`.
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> More information: <https://netpbm.sourceforge.net/doc/pnmnorm.html>.
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- Force the brightest pixels to be white, the darkest pixels to be black and spread out the ones in between linearly:
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`pnmnorm {{path/to/image.pnm}} > {{path/to/output.pnm}}`
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- Force the brightest pixels to be white, the darkest pixels to be black and spread out the ones in between quadratically such that pixels with a brightness of `n` become 50 % bright:
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`pnmnorm {{[-midv|-midvalue]}} {{n}} {{path/to/image.pnm}} > {{path/to/output.pnm}}`
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- Keep the pixels' hue, only modify the brightness:
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`pnmnorm {{[-k|-keephues]}} {{path/to/image.pnm}} > {{path/to/output.pnm}}`
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- Specify a method to calculate a pixel's brightness:
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`pnmnorm -{{luminosity|colorvalue|saturation}} {{path/to/image.pnm}} > {{path/to/output.pnm}}`
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