JPEG Quality

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extremis

JPEG Quality

Post by extremis »

JPEG Quality is generally determined by the selection of quantization tables and downsampling.
Is there any way to detect if a jpeg image is downsampled or not and view its quantization tables?
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anthony
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Re: JPEG Quality

Post by anthony »

extremis wrote: JPEG Quality is generally determined by the selection of quantization tables and downsampling.


That sounds more like GIF not JPEG. JPEG does not quantize the image to a fewer numebr of colors, but attempts to map a frequency (fourier transform) to generate higher lossy compression.

As for your question. Glenn?
Anthony Thyssen -- Webmaster for ImageMagick Example Pages
https://imagemagick.org/Usage/
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