Working in 48 bit .

[snapperanton]

I have just upgraded to Ai from SE to enable me to scan 16 bit images into Photoshop. Unfortunately when selecting 48 bit in Ai there seems to be minimal control over the scanning procedure.

My question is this. Has anyone noticed any difference in quality between an image scanned at 48 bit then converted into 8 bit via Photoshop COMPARED TO an image scanned straight into Photoshop at 8 bit.

I am using an Epson 4870 scanner and am trying to achieve the best possible scans for reproduction in magazines and books.

Any ideas??

[kmart]

There is a big difference when you scan raw 48 bit images over 8 bit scans. In 48 bit you are getting all the color information there is, where as with 8 bit your not capturing all there is, and when you edit the image and color correct it in PS you are degrading the image further
My workflow is to scan in 48bit HDR and then open the raw scan in SF HDR where you can correct your color and sharpen the image with very little loss of quality. I bring the edited image into PS as 16bit for final tweaking.
Most magazine publishers have a minimum of 50 megs. for any images. You wont get that by scanning in 8bit.

If you do not have HDR then try scanning in 48 bit Color, then you will be able to edit in AI.

[snapperanton]

Hi. Thanks for the reply. I think I may have mislead you a little in my original post. When I refer to 8 bit images, I meant per channel (as in PS) . Up until now I have always had pro drum scans done from my work. They are always supplied as 24 bit (8 bit per channel) which I work on in Photoshop and supply straight to the magazine, 40-50 mb per page. This seems to be a standard in the industry. Also, up until recently it hasn't been possible to work 100% in PS (until CS) with 16 bit per channel images.

So I guess what I really meant is this: If I use the 48>24 bit scanning Mode in Silverfast Ai (producing an 8 bit per channel PS tiff) will I notice any considerable lack in quality compared to using the 48 bit HDR colour mode, then converting to 24 bit (8 bit per channel) in Photoshop. I have only had the software 2 days but the 48 bit HDR mode seems to not allow any colour changes etc to be made. The Epson software bundled with the scanner allows full control over 48 bit scanning, but I feel it is a less superior software for professional scanning.

Any ideas?

[snapperanton]

after looking again at the software I now notice the two options 48 bit color and 48 but HDR Color!! Hadn't seen the 48 bit color option previously. I blame the lack of concentration on my 6 month old baby!!

What is the difference between HDR and non HDR ??

[degrub]

48 bit allows you to have color adjustments available when you scan.
48 bit for HDR is just that: no color adjustments. THe intent is that you will edit the image and make adjustments using HDR later.

Take a look at Ian's HDR tutorials at
www.computer-darkroom.com/sf5_contents.htm

Of course, with both you can make adjustments with PHotoshop later.

Frank