8 v 16 bit scans Imacon sharpening

[david_southwood]

I have an Imacon precision 2 scanner and have been making scans at 8 and 16 bits to see what the differences are.

 

I can perceive no difference between the two. I am looking mainly at the colours, as opposed to sharpness and

contrast. Am I blind, or looking in the wrong places?

 

In an attempt to obtain the 'rawest' scan I have turned all automatic functions like sharpening off. Does anyone

have experience with the scanner, and if so is this the right move? Someone once told me that the old Imacons had

a default sharpening filter which was always on...

 

Thanks

[michael_morris3]

While you may not see a difference in 8 V 16 bit the differences will become obvious as soon as you make any adjustments, especially

exposure or brightness. I only use 8 bit images for printing. All originals are stored in the highest precision possible.

 

----------------------

 

Michael Morris

[ellis_vener_photography]

"I am looking mainly at the colours"

 

Which color space are you using to scan into? What is the subject matter? If you are using Adobe RGB(1998) as the color space you need to be aware that you could definitely be clipping some color that is in your transparencies -- but that really depends on subject content

 

What level of display are you looking at? How is it calibrated and profiled?

 

There is a great software tool used for analytically looking at the color data in an image and see what color is in and out of gamut for a range of color spaces or various device profiles . It is called ColorThink 2.2 and comes from http://www.chromix.com

 

"Someone once told me that the old Imacons had a default sharpening filter which was always on... "

 

Some one told you correctly . I believe the USM setting you need to actually completely turn off the default sharpening is -142.

[ellis_vener_photography]

One more more thing: How are you adjusting the dynamic range of each scan? With transparencies the best setting is to leave the black clipping point at 0 (zero) but to bring in the white clipping point to about 5-6 points beyond the right edge of the histogram's "mountain range".

[Lou_Meluso]

David, I don't have the Precision 2 but an Imacon 848 and Flexcolor. Yes, you must drop the sharpening level to it's lowest negative value to completely disable it. However, what I found is if you do that neither smart sharpening nor unsharp mask in PS can fully recover the sharpness in the original. Some may disagee with this but that's what I found in my testing with my scanner. I use a sharpening value of -75 during the scan. It still comes in plenty soft but snaps up cleanly in PS. BTW, not only should you scan in 16-bit but sharpen in 16-bit as well. Most folks will tell you that sharpening is the last thing you should do before outputting a file to print or web. I suggest that the last thing you do is drop to 8-bit.................................Lou

[david_southwood]

Thanks for these replies. All my suspicions have been laid to rest.

 

Sharpening: under 'Texture' in my Imacon setup dialogue box is the relevant sharpening section, I think. There is an 'Apply' button which I previously had unticked. To neutralise the sharpening, actively, I suppose I need to engage the filter and turn in to -200 which is the maximum negative value. Does this sound right?

 

Tests are underway as we speak.

 

I also think that a miniscule touch of sharpening on scanning(or shooting a RAW) can produce the sharpest results without looking overdone.

[rodeo_joe1]

Sharpening isn't affected by the bit-depth of the image; colour, saturation and levels adjustments are.

 

As already mentioned, you'll only see the difference if you make quite drastic changes to these parameters. In any case a standard computer monitor and video card are only capable of showing an 8 bit (24bit colour) image, regardless of the file bit-depth, and standard inkjet photo-printers are even worse, showing a dithered selection of colours from a pallette of only a few hundred.

[new_haven]

There is a thread at

 

http://groups.yahoo.com/group/imaconusers

 

that address this question--

 

Hi,

 

I asked Hasselblad support about Imacon sharpening and got the response below. Note that different settings are

needed for Tiff and 3f scans if no sharpening is wanted.

 

 

 

Yes that is correct. If you do not want to add sharpness to your Tiff scan (made from a preview scan) UMS must be

set to -120 and the check box must be checked.

 

A value of 120 USM will always be applied to 3f scans. If you do not want to add any extra USM to your 3f scans

USM must be set to 0 and the check box checked.

 

Best regards,

 

Anne-Marie

Hasselblad Technical Support

www.hasselblad.com

[iliafarniev]

Hi. I have been experimenting with Imacon generated 8 and 16 bit files of the same shots and non-Imacon 48 bit

color RGB files of similar kind thorough last 4 days. Concluded very quick that 16b and more make file much more

supple and yelding to any kind of editing in PS&Co. It probably takes an experiensed eye to se the difference

between 8b vs. 16b vs. 48b but it is there. Even viewers perseption of "sharpness" does change dramatically. The 8b

sharp image often leaves average viewer unsatisfied and they often says it is not sharp enough. Same shot with

same sharp at 48b plays them on much better.