Colorspace RGB -> Log question

[stevepugh]

Hi all,

Yet another colorspace question for you...trying to generate a Log colorspace DPX file (in this case, a slate image which starts as a PNG, gets text drawn on it, and gets saved out). So far, specifying "-colorspace Log" fails to give me a logarithmic image, as "identify -verbose" still indicates RGB colorspace.

I've recently read that the "-colorspace" option is only for internal handling, and that to change the colorspace of a file you are writing, one must use the "-type" parameter. However, I do not see a "-type Logarithmic" or somesuch.

Am I barking up the right tree?

Thanks,
Steve

[fmw42]

It works for me.

I don't think IM reports anything but RGB and Gray and such for colorspace. It does not store that information. I had requested it before. Nevertheless,

convert -size 128x128 gradient: grad128.png

and then convert grad128.png -colorspace LOG grad128log.png


you will see that the second one shows a logarithm application to the linear gradient.

[anthony]

Log appears to be an interesting colorspace...

Try and compare the output of these commands...

Code: Select all

convert -size 128x128 gradient: x:
convert -size 128x128 gradient: -colorspace LOG x:
convert -size 128x128 gradient: -negate -colorspace LOG -negate x:

Any idea as to what 'log' colorspace does, and if there is an inverse to it?