Convert images to RGB and strip metadata

[ausi]

Fixes #34

Blocked on contao/imagine-svg#7 and php-imagine/Imagine#564.

[discordier]

LGTM, however, the upstream PR seems to break stuff.

[aschempp]

does that work with all implementations? Or will we get an exception e.g. when using GD?

[ausi]

Yes, it works with all Imagine implementations. In GD strip() and usePalette() just do nothing, because GD strips always and converts always to RGB.

[leofeyer]

It seems that the GDlib does not handle palette conversions very well:

http://stackoverflow.com/questions/12815305/bad-cmyk-to-rgb-conversion-with-gd

Therefore, do we really need this step?

[ausi]

With GD, the behavior before and after this pull request is exactly the same, see #37 (comment)

But with Gmagick and Imagick, the image is converted to RGB and profiles and metadata get stripped from the image.

We can make the conversion to RGB configurable, I’m not sure if strip() should be configurable too.

[leofeyer]

With GD, the behavior before and after this pull request is exactly the same,

Ok, sorry for not reading thoroughly. Then we do not need this to be configurable I think.

[Toflar]

The only problem I see here is that resizer settings should be considered in the cache key.

[ausi]

The only problem I see here is that resizer settings should be considered in the cache key.

If we don’t make them configurable, they are not “settings” I think and are not needed in the cache key then because they can’t change.

[Toflar]

Fine with me then :) I think I'll only test it on a real life project once the php-imagine/Imagine#564 discussion has found an end, ok?

[ausi]

I think you can test on real life project already. It looks like the issue from php-imagine/Imagine#564 was related to my installation of ImageMagick because the delegate lcms was missing. You can test that on your system by calling convert -list configure | grep DELEGATES and if lcms shows up, everything should be fine.