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Author Topic: Sharpening Artifacts?  (Read 1670 times)

pflower

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Sharpening Artifacts?
« on: November 23, 2011, 01:58:31 pm »

Not sure if this really belongs in the LR forum, but since I printed out of LR...

Can anyone help me to understand this.  I printed an H3D-39 file on A2 - Ilford Gold Fibre Silk.  LR showed it at 348ppi at approx 15x19 inches so I picked the resolution as 360.  The image contained large areas of smooth toned sky and a metal wall.  The print however showed a sort of "waffle" effect over the smooth areas - as if someone had stamped all over it with a waffle iron.  This wasn't particularly strong but was very noticeable.

I finally realised what was causing the problem - I was printing from a Tiff file that I had, most probably, exported from LR some time ago and which included some sharpening (most probably in the region of 65,1,25 - which looks pretty good at 100% on screen).  Before printing the .tiff I applied much the same sharpening again in LR.  Removing the extra sharpening resolved the problem and the file printed beautifully with clean, smooth tones.

Curiously looking at the file at both 100% and 200% showed no indication that it was over-sharpened. The sky and wall areas looked clean and showed even "grain".  Why should this additional sharpening have caused this effect?  Sharpening has always been a bit of a mystery to me,but this was not a case of the sharpening causing halos around edges - it completely muddied what should have been a smooth tone with no detail in it.

Any explanations?

Can anyone shed any light on
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madmanchan

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Re: Sharpening Artifacts?
« Reply #1 on: November 23, 2011, 03:27:44 pm »

I'm not following you entirely. It sounds like the "waffle" print was sharpened twice, right?

The file that you inspected at 100% or 200% -- was that with 1 round of sharpening applied, or 2 rounds?
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Eric Chan

pflower

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Re: Sharpening Artifacts?
« Reply #2 on: November 24, 2011, 07:49:39 am »

Eric,

Yes.  What I have now worked out what I did was export a 3FR file from LR to a 16 bit tiff with my normal level of sharpening (usually around 60, 1, 25).  This looks good on screen at 100%.

Having forgotten that the .tiff had been sharpened, I then sharpened it again in LR with the same amount of sharpening  and then printed it. Effectively the same file had been sharpened twice (once for the export) and then once before sending it to the Print module. This printed with the "waffle" effect.  For a while I couldn't work out what was happening or what was causing this - I originally assumed a printer problem but there were no blocked nozzles and I did a head alignment.  Printing the original 3FR file (with only 1 iteration of sharpening) produced a good print and so I removed the 2nd iteration of sharpening from the .tiff which also then printed normally.

When the twice sharpened .tiff was viewed at both 100% and 200% on the screen there was no indication that anything was wrong with it.

I have solved the problem but am curious as to what caused this effect. 

Anyone got any ideas?

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