Export problems to jpg

Question

Hi all,
I'm using Indesign CS3 5.0 with Windows Vista, and having problems exporting to jpg. Help is highly appreciated!
In brief, when exporting to jpg:
* Settings:
Export Spreads,
Quality high,
Format method baseline,
Resolution 600ppi.
Also several variations are used.
* Issue:
Some, but not all, pages show a horizontal 'band' of lighter color.
My problems are identical to those posted but not solved last February by Alyson Clemons. She also posted some examples, see
http://www.adobeforums.com/webx?128@@.3c06458a
I also have the problems described by Alyson regarding PDF export, but I won't go into the those here; the JPG export is the most important for my purposes here.
Thanks for your help!
RUUD

Answer 1

First, black is not necessarily the same color in all spaces, especially in CMYK. Black ink alone is going to look gray compared to any black areas in any image, which are always "rich blacks" composed of both Black and lesser amounts of C,M and Y, or of a mixture of R, G and B components that will be converted into a CMYK mix at print time.
Among other things this allows for a much broader range of shade in the blacks (and consequently better shadow detail reproduction). The exact mixture is calculated to fit the characteristics of papers and inks in use on various devices, and is designed to give as dark a black as possible without using so much ink that it puddles or offsets onto the back of the next sheet before it dries. Some papers and printing technologies can handle more ink than others, so you will see darker blacks in those spaces.
No matter what color you choose as your "black" background you are going to see transition borders in at least some areas where images are placed on top of it, simply because the background is uniform, and the image is not. Using a black formula from one of the images can help, but won't hide everything.
> There is only 1 page that uses transparency, but it is lost in the PDF. I don't mind that the page is flattened but now the partially transparent objects are opaque in the final PDF, completely masking the underlying text.
Transparency flattening is achieved either by calculating the values of the colors created by the overlapping objects if they use a process color or RGB, or by using overprinting for spot color inks. You should not be using spot colors in your design unless you actually intend to use a press and spot inks. Without seeing the file, I couldn't begin to guess what's going wrong precisely, but it is most likely a combination of your flattener settings and the PDF export options.
You might find either, or both, of these articles helpful:
http://indesignsecrets.com/eliminating-the-white-box-effect.php
http://indesignsecrets.com/eliminating-ydb-yucky-discolored-box-syndrome.php
Also, it is generally considered good practice to keep text above any transparent objects to avoid having it rasterized or converted to outlines, but this isn't always possible, and may not be much of an issue for you in this project.
Peter