SOLVED: -quality and MIFF

[snibgo]

In http://www.imagemagick.org/script/comma ... hp#quality , under quality, documentation says:

For the MIFF image format, quality/10 is the zlib compression level, which is 0 (worst but fastest compression) to 9 (best but slowest). It has no effect on the image appearance, since the compression is always lossless.

However, trying quality from 0 to 99 shows no difference in resulting file size, and only minimal difference in speed, probably a natural random variation.

Code: Select all

convert in.tiff -quiet -quality NN out.miff

Is the documentation wrong? Is there a bug? Is my understanding wrong?

[dlemstra]

You should also set the compression to zip

[snibgo]

Ah, yes, adding "-compress zip" means that varying "-quality NN" gives different sizes. Thanks.

[snibgo]

For anyone interested, TIFF works in the same way as MIFF: with "-compress zip", varying "-quality NN" gives different sizes. Perhaps someone could add to the documentation that what is said about MIFF here also applies to TIFF.