snibgo

"-colors N" first checks whether the image is has RGB channels. If doesn't, then it is silently converted to sRGB. You can use "-set colorspace sRGB". This changes the metadata...

The JzAzBz colorspace typically uses a very small range of values: ``` magick testBars.png -colorspace JzAzBz -verbose info: Channel 0: min: 0 (0) max: 4.48291 (0.01758) Channel 1: min: 123.357...

The JzAzBz colorspace typically uses a very small range of values. If we stretch those values to a range closer to the maximum, color reduction will create more colours. After...

I confirm the problem. `-resize` is not relevant. The problem can be shown by: ``` magick test.tif out.tif ``` ... using IM v7.1.1-38 downloaded today, and then viewing test.tif and...

@gursch: How was test.tif created? Was it with Adobe Photoshop? A workaround for the misreading of the meta channel: ``` magick -define tiff:assume-alpha=true test.tif x.png ``` This will set the...

> The TIFFTAG_EXTRASAMPLES (one extra sample) are set to EXTRASAMPLE_UNSPECIFIED instead of EXTRASAMPLE_ASSOCALPHA or EXTRASAMPLE_UNASSALPHA and that means we don't treat the extra channel as an alpha channel. That is...

I agree with your result, and that this is a bug. "`-compose Dst`" has a similar problem.

> identify claims that files like this are "8-bit sRGB", ... No. `identify` claims nothing about the file. Instead, it describes the image that has been read into memory.

> Using "-define tiff:alpha=associated" makes the background transparent, but modifies the semi-transparent areas of the image Associated alpha "premultiplies", ie it multiples each colour sample by alpha before saving. If...

I've had a quick look at IM's source, and I don't think IM does any alpha associated or unassociated processing when saving TIFF files. It just sets a flag. I...