Combs

OK I take my TIFF file developed in Silky and load it into PS.

The histogram is a continuous block. I add an adjustment layer, levels, mess with the three sliders and I get a histogram like a comb.

Why?

Thanks

Mike

Because after manipulating the image some values of pixel are entirely missing, hence the comb effect. If taken too far, this would be seen in a print as a form of banding in areas of gradation.

Nothing I can do then?

Mike

You'll get less of the comb effect with RAW.

I also think that the effect is less pronounced if you use 16bit TIFF files.

I wondered about 16 bit - and iceblinker are you suggesting I use the Adobe RAW converter rather than Silky?

Mike

For highest quality convert your Raw files to 16bit Tiffs. Theres a lot more information for PS to work with.

That's true, but it also precludes quite a few of the functions in Photoshop. At the end of the process you will still need to convert to an 8-bit TIFF for most purposes.

I just meant do as much as possible on a RAW level before converting to TIFF (or JPEG) with whatever program you prefer. But I appreciate that Silkypix may not do all you want.

I don't know if it would be beter to use Adobe RAW rather than Silky. Perhaps not despite the "comb effect".

Sorry my reply wasn't much use. Not one of my best

As stated, Silkypix isn't the "problem" - it's pushing an image too far You'll get that whatever raw converter you use.
Pete is correct - do as much as you can in the RAW software. If you have an area that need significant work apart from the main image then process twice in SP - adjusting the settings for each area. Then blend the two images in Photoshop.

Once I did see a histogram smoother plugin... can't remember where though!!

A quick tip though... if the banding become apparent then adding some noise to that area often helps break up the banding. Most controlled way is: 1) add a new layer, 2) fill with grey, 3) add noise, 4) change layer blend mode to "Luminosity", 5) Add a layer mask as needed.

HTH!
Matt

PS. Here's a sample of the two-step-processing approach.

EDIT: Histogram Repairer

As they mention, if you use 16-bit images (ie processed from RAW to 16-bit TIFF) then you don't need to repair the histogram.

This might be worth a read... though take with a pinch of salt. Some gaps are fine - until you can see the posterization in the final image (And the add-noise technique is normally just fine).

Matt

Thanks guys I'll see how I get on and report back.

Mike

I'm always converting from SilkyPix to 16 bit TIFF. When working in Photoshop I do see the 'comb' from time to time. Usually when you let Photoshop redo the histogram it gets back to normal. But I only do that when I fear that posterization (I think that is the correct term for the banding that John mentioned) might have occurred.

Prieni

PS doesn't update the Histogram display automatically (it would take resources away from everything else) so its just the display that's lagging behind, clicking on the yellow triangle forces PS to update the display and the combs disappear. Rest assured that the combs aren't there in the file its just the display that hasn't 'caught up'.