converting to greyscale darkens my images

[adopey@adobeforums.com]

I often have to import postscript images (with bitmaps embeded) into AI 10 and frequently need to turn them into greyscale and add some text etc.

My problem is that turning images to greyscale (from rgb) in AI makes the image darken and lose much of its detail.

I tried converting the image to grey in photoshop first, then imported it into AI but when I saved the final eps, the file jumped from 13mb to about 65mb!

does this mean illustrator converts all bitmaps back to cmyk/rgb upon import??

unfortunately (in this instance) size does matter and if there is a way to keep
these file sizes down to the 'normal' greyscale size then I really need to find out

TIA

[Tim_Murray@adobeforums.com]

Please describe more about the file you start with: What it looks like, how it was made, etc.

[adopey@adobeforums.com]

I am afraid the creation of these files is a bit of a mystery as they are sent by scientists from all over the world.

The files in question seemed to be RGB bitmap images that looked greyscale to the naked eye and they were provided in .ps format. When converting to grey in photoshop however, I saw virtually no change in 'brightness' to the image as opposed to a drastic change in AI10 (but eventually ran into the 'giant filesize problem' as described above)

I find it hard to believe that this problem has never occured before but I am completely baffled at the moment. Just when I thought I had grasped the Whole 'image format/filesize' thing along comes a new hurdle...