Why is it so tedious to change multiple pages in a PDF to B/W?

Using Enfocus PitStop Pro, it is possible to enter in a “discontinuous” range of pages that an Action List can process:

There may also be a similar approach using the Callas engine licensed in Acrobat Pro, or perhaps by adding Callas pdfToolbox as a third party option.

I find this thread rather interesting from a few points of view.

First of all, there is a capability to do color conversions for all, a single, or a range of pages. For example to go to grayscale:

Obviously, what is being requested is a facility to specify multiple separate pages or range of pages. There is no built-in way of doing this. Perhaps JavaScript can be setup for this although, quite frankly, by the time you were done, it would probably take as much time as it does to invoke the Convert Colors dialog multiple times.

However, one should note that virtually every PDF workflow system has such a capability of doing color => grayscale conversions as well and if you are sending the color pages to one printer and the monochrome pages to another, this might be something that you can handle at the RIP/DFE.

More importantly, though, is that conversions to grayscale often yield results that are not particularly pleasing, whether the content is colored text, vector, or raster. Such conversions lose the contrast of one color versus another. Objects in two totally different colors may appear exactly the same when converted to grayscale. One will note that in Photoshop, all sorts of options including “filters” are provided to guide conversions from color to gray following what used to be done in film-based black and white photography. For scenic photography, it was quite common to use yellow, orange, or even red filters over the lens to darken the sky, bring out the clouds, and contrast with the non-sky scene. Bottom line is that for pages to be printed in grayscale (i.e., black and white instead of color), color content needs to be carefully converted prior to PDF creation for optimal if not even readable results.

          - Dov

The only alternative that I can think of offhand is to convert an entire copy of the original file to mono, then use the tools/pages/replace feature to manually replace the various pages with the original full colour versions.

This is more a feature request then a technical problem that needs to be solved.

It would be for me interesting to see why you are looking for changing the pages in bw and why the pages are in colour to start with, if they do not need? If you use on your page design only the K component, it will be a bw page.