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PNG quality after conversion

Posted: 2020-03-26T10:37:22-07:00
by colorful
The input PNG file has quality 50.

If I were to convert the PNG to PNG without specifying the quality,
will it become 75 (default quality) or retain the original 50?

How come PNG quality does not show when using the identify tool?

Re: PNG quality after conversion

Posted: 2020-03-26T10:53:59-07:00
by snibgo
For PNG, the "-quality" setting has no impact on quality. It affects filesize only. It controls some parameters used for compression. Those parameters are not stored in the file, so IM cannot reconstruct the quality setting that was used.