PNG quality after conversion

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colorful
Posts: 6
Joined: 2020-03-04T11:55:05-07:00
Authentication code: 1152

PNG quality after conversion

Post 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?

snibgo
Posts: 12894
Joined: 2010-01-23T23:01:33-07:00
Authentication code: 1151
Location: England, UK

Re: PNG quality after conversion

Post 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.
snibgo's IM pages: im.snibgo.com

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