[reportlab-users] Reportlab and colors in Adobe Reader

Robin Becker robin at reportlab.com
Wed Aug 11 10:58:08 EDT 2010

On 11/08/2010 14:04, Miha Tomšič wrote:

> Hello!


> I found this on Adobe forums for a similar problem:

> "You need to set the transparency blending space of the page to RGB,

> since the default blending space is CMYK (hence the color shift). You

> do this by adding a transparency group dictionary to the page's

> dictionary when creating the PDF."


> Can this "set the transparency blending space of the page to RGB" be

> done in ReportLab? Isn't ReportLab's colorspace RGB by default?


> Thanks and take care,

> Miha

So far as I know we convert png into RGB, but we don't have a concept for the
standard/default colour space.

As I read the 1.7 manual I think we need to put these exceptional things into a
transparency group XObject (which is like an ordinary Group XObject, but with
extra parameters) and set some special parameters on the group.

So far as I know we can't do that at the moment; firstly we don't yet have group
XObjects, secondly I don't think we understand exactly how they are used.

It may be these are just forms with an additional entry in the dictionary, but
I'm not sure.

We do support cmyk for JPEGs, could that be a possible solution?


> On Wed, Aug 11, 2010 at 8:19 AM, Miha Tomšič<miha.tomsic at gmail.com> wrote:

>> Hello, Steve!


>> Thanks a lot! Looks the way it should.


>> Take care,

>> Miha


>> On Tue, Aug 10, 2010 at 4:50 PM, Steve Romanow<slestak989 at gmail.com> wrote:


>>> Here is what it looks like in SumatraPDF on win7.


Robin Becker

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