[softwarelist] Re: JPEGs files in PostScript

In article <C06D5790.1984C%akalat@xxxxxxxxxxx>,
   Mike Williams <akalat@xxxxxxxxxxx> wrote:
> If I have an Ovation Pro document with colour JPEGs embedded. I am then
> outputting to PostScript (PostScript 2 driver) with the colour option
> not enabled. The PostScript file is then distilled on a Mac and viewed
> in Acrobat. I would expect, with sprites for example, for all colour
> images to appear in monochrome, but in a recent example with embedded
> colour (RGB) JPEG images some appear to have been converted to
> monochrome, while some remained in colour.

> Can anyone tell me what happens to embedded colour JPEG images when
> outputting what should be a monochrome PostScript file?

When printing to PostScript with the colour option off, RGB sprites will
be converted to 8bit greyscale and hence suffer from being chopped into
many smaller bitmap images (as is usual with the PostScript driver).

JPEGs on the other hand don't, and will appear in full colour in the
resulting PostScript output.

If you find that some of your JPEGs are being converted to greyscale
images it is because OPro is sending them as sprites to the print
stream. Most likely, this is because you have some 'image processing'
applied to the JPEG in OPro, which then has to deal with it as a sprite,
so will print it as a sprite.

There is a small problem with OPro in that once image processing has
been applied to a picture it cannot be removed, even if the Default
button is clicked. It is the picture fame that retains the processing
settings, so even if you drop a completely different picture into the
frame OPro still handles the picture as if it's a sprite.

The only way to remove the 'processing' effect in the frame is to
 1. delete the picture from the fame,
 2. type some text to convert it to a text frame,
 3. delete the text,
 4. and drag the picture back into the frame.
Then OPro will forget the processing state of the frame and JPEGs will
once again be handled as JPEGs when printed to PostScript.

If you want the images to be monochrome in the final output, then it's
best to keep them as JPEGs but first convert them to greyscale images in
a bitmap editor such as DPScan / PhotoDesk / Photoshop etc.

-- 
Gavin Crawford
email: gav@xxxxxxxxxxxxxxxxxxxx
  web: www.crawford-print.co.uk

Other related posts: