A greenish artifacts seen on B&W scans in dark areas...

[alexz]

Having quite a bit of 35mm scanning experience (with Nikon LS-40), just recently I begun to notice weird artifacts, most on B&W scans in darker areas. There are some greenish artificial areas (there are definitely no such in the source image) - presumably it an outcome of scanning. These are most noticeable in B&W shadows and dark areas and the artifacts are heavily influenced by hystogram tweaking. Jsut squeezing a bit Level at the shadow side either moves the greenish area away ot they are vanished at all but may appear on other darker areas.

After experiencing these several times with my B&W scans (usually scan negs to 8 bit), I thought it may be some issue with insufficient dynamic range so switched to 12 bit scans - still the artifacts are there.....

I'm attached the sample file to let you see what I'm talking about. Just check the girl's hair area at the front (best seen on the screen in darker ambient illumination).

The artifacts appear on both TIFF and JPEGs.

Any opinions/experiences ahdt it can be and how to cope with it ?

 

[JoeV]

What Green?

What Green?

Sorry, I can't see any color artifacts. Your monitor may be aging, causing the shadow areas of images to have a green-ish color caste.

I typically scan B/W film using 16-bit; doing so ensures that there is no color component (although you can't use the channel mixer technique on 16-bit B/W files).

 

[oscroft]

Nope, I can't see any green either

 

[Ronald M]

Can`t see it at all.

 

[alexz]

Xmm, weird...don't know what to say...
My monitor is Samsung SyncMaster 997B, abot one and half years old, I'd think unlikely to produce such effect. Strange indeed...

 

[Avotius]

im afraid that I dont see anything either, I have a calibrated ezio flexscan 19 lcd and I dont see anything at all. I suggest it might be a monitor or calibration problem

 

[iml]

No green here either.

Ian

 

[alexz]

Xmm, the monitor was last time calibrated about a half year ago, I'd tend to think that might be unlikely the reason, but God knows...
perhaps I'll try to re-calibrate it soon...

 

[VinceC]

No green here. NEC MultiSync LCD1700.

 

[jairy hunter]

I've seen a greenish cast to shadowy areas on prints of CN400; usually when I PS them, I just change to Lab color and select the lightness channel, grayscale, then do the processing. That usually gives me a nice b/w to adjust curves, make duotones, whatever-->DON'T FORGET TO CHANGE BACK TO RGB COLOR or you can't save as a JPG/TIFF.....

 

[rpsawin]

Alexz,

I can't see any green either. BTW does this happen with all emulsions or just specific ones?

Bob

 

[alexz]

Thank you all.
Well, in fact I begun to notice taht relatively recently, and mostly on B&W (but I suspect it is there on color either on dark areas). Since no one of you was able to figure the effect on the attached image while checking on your monitors, I assume it si somethign to do with my monitor/graphics setup probably...strange indeed...

 

[JoeV]

Monitor's White Balance

Monitor's White Balance

Most monitors (at least CRT-type monitors) have internal service adjustments, or software adjustments, for 'white balance'. There are usually two sets of white balance adjustments, one for the shadows or 'low lights', and the other for the 'high lights'. Also, as a CRT's guns age it is not unusual for either or both of these to go out of whack.

To get your monitor back 'in whack' you may need to have it recalibrated, especially the low-lights.

But just to be sure it is the monitor, try scanning film in 16-bit B/W mode. There should absolutely be no color cast to the resulting image, low-lights, midtones or high-lights.

~Joe

 

[Kameran Kashani]

I don't see any green cast either.

As far as recalibrating CRT monitors, it sometimes has to happen with annoying frequency. Years ago, I worked for a computer manufacturer that did business with Pacific Data Images (PDI, now Dreamworks Animation SKG.) At the time, their animators used top-of-the-line CRTs which, if I'm remembering correctly, were recalibrated on the order of every 6 months.

YMMV.