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Is 48-bit Scanner Really Needed?  
User currently offlineJ_hallgren From United States of America, joined Jun 2000, 1507 posts, RR: 0
Posted (12 years 10 months 1 week 6 days 12 hours ago) and read 1434 times:

Ok, so I'm not much of a real av-photo person BUT I know that you folks have knowledge of things like this, so I ask....

Question from potential scanner buyer is: Under what conditions will I be able to use the 48-bits?

Since my LCD on laptop is max'd at 24 bits as I understand it...and the Visioneer 8900 specs say it outputs only 24 bit EXCEPT to Photoshop LE which I don't quite follow...

Anybody have any info to clue me in? Thanks!!





COBOL - Not a dead language yet!
6 replies: All unread, jump to last
 
User currently offlineCkw From UK - England, joined Aug 2010, 769 posts, RR: 16
Reply 1, posted (12 years 10 months 1 week 6 days 7 hours ago) and read 1402 times:

I think what is meant by the specs is that you need Photoshop to be able to manipulate a 48bit tif - and even then the amount of manipulation you can do is very limited. I think only PS ver. 6 provides true 48bit (16 bit mode) editing.

You are correct in saying you will see no difference on your LCD screen between a 24 bit and 48 bit scan. The difference is the "head room" you gain to make adjustments to the image. The more data the software has to work with, the smoother the tones of the final image.

For example, if you try and brighten a shadow area - in 24 bit images, anything more than a minor adjustment results in "gaps" the tone curve which can appear as less the smooth tonal transitions - working with 48 bit images lets you make larger adjustments and still retain smoother tones in the shadows. Against this, you will be working with a file 2x the size, so memory & processor power become an issue.

Cheers,

Colin



Colin K. Work, Pixstel
User currently offlineCfalk From , joined Dec 1969, posts, RR:
Reply 2, posted (12 years 10 months 1 week 6 days 7 hours ago) and read 1397 times:

That's interesting Colin. So would that mean that if I have a photo that needs significant touching up, like gamma or brightness, that the results would be better if I scan at 48-bit, make the changes, and as a last step save as 24-bit jpeg?

Charles


User currently offlineCkw From UK - England, joined Aug 2010, 769 posts, RR: 16
Reply 3, posted (12 years 10 months 1 week 6 days 3 hours ago) and read 1383 times:

Charles - yup, that's basically how it works ... but you have to get the workflow right, as not all tools/filters work on 48 bit images, even in PS6. But when it comes to levels and curves, I think you'll be surprised how much more room you have to manouever.

Though it won't work miracles ... an underexposed pic with no shadow detail will still look like an underexposed pic with no shadow detail  Smile but if the detail is there, just a bit lost, working in 48 bits (16bit mode) seems to help a lot.

Cheers,

Colin



Colin K. Work, Pixstel
User currently offlineCfalk From , joined Dec 1969, posts, RR:
Reply 4, posted (12 years 10 months 1 week 6 days ago) and read 1376 times:

Thanks for the tip Colin. I'll try that. That would probably be quite usefull with bad weather shots.

Cheers,

Charles


User currently offlineJ_hallgren From United States of America, joined Jun 2000, 1507 posts, RR: 0
Reply 5, posted (12 years 10 months 1 week 2 days 21 hours ago) and read 1349 times:

Thanks to Colin (and Charles)for the replies!

Your Q&A helped explain it...found later that the Epson scanner I am trying ALSO states it outputs only 24 bits (in quite small print)...so I guess the other 24 bits end up in the "Bit Bucket" UNLESS you have the higher level software on the receiving end...

I can see how making changes in 48 bit mode would improve the result, even in 24 bits, after reading a "bit" in some PhotoShop books.



COBOL - Not a dead language yet!
User currently offlineSia jubilee From Hong Kong, joined Feb 2000, 145 posts, RR: 1
Reply 6, posted (12 years 10 months 1 week 2 days 1 hour ago) and read 1336 times:

indeed! We definitely need this 48 bit input.
Because of the lost during scanning.
maximum inputting is needed.
That makes sure the output on screen(the file) is in the best quality. More detailed scans.

Alan Tsui
Hong Kong


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