• Registered: 2010-05-19
  • Posts: 5

Topic: Artifacts in Image Analyzer display - at 1:4 and greater

Editing a 4000 x 3000 24bit image at 1:4 >up I am getting these sort of artifacts
in the image display

http://i301.photobucket.com/albums/nn61 … ifacts.jpg

below is the original picture state (shown resampled to 1000 x750)

http://i301.photobucket.com/albums/nn61 … ifacts.jpg

The artifacts make it difficult to know what is really happening to these type of images when editing. Any help appreciated.

I run Image Analyzer on a 14" lcd, hp laptop running vista.

The pics are from a Panasonic Lumix fz35.

  • From: Portugal
  • Registered: 2004-02-04
  • Posts: 45

Re: Artifacts in Image Analyzer display - at 1:4 and greater

Hi...
The "artifacts" that you see are called "Moire Patterns"
and are very common...
Usually found with crossstiched or real fabrics photo ...
It depends on the zoom level ...
If you see the picture in 1:1 they are not present...
it also depends on the De-Bayer algoritm of the machine...

If you search on the web regarding "Moire patterns" you will have more info...

Mark Marques

MarkMarques's Website

  • Registered: 2010-05-19
  • Posts: 5

Re: Artifacts in Image Analyzer display - at 1:4 and greater

Hi Mark Marques, thanks for the reply and info. What I need to know is how to deal with the moires and contrast blowout when I'm trying to edit a picture.

They don't show up in Photofiltre, but do in Irfanview and Image Analyzer.
I can't figure out why that is?
Unfortunately, Photofiltre isn't compatible with photoshop filters, which I use.

  • From: Portugal
  • Registered: 2004-02-04
  • Posts: 45

Re: Artifacts in Image Analyzer display - at 1:4 and greater

After some info I have found that both IA and IrfanView
do use a specific  ( I do not know the correct algoritm name)
to "display and resize" the image...

As far as I know I do not know if it is possible to
choose a different algoritm to re-display the image...

Perhaps redimensioning the image window to different size
(varying the window size by an odd or even number of pixels) will gave some improvement...

MarkMarques's Website

  • Registered: 2010-05-19
  • Posts: 5

Re: Artifacts in Image Analyzer display - at 1:4 and greater

Thanks for the info again, Mark. I think I will try the irfanview forums and see if anyone there knows what's going on.

  • admin
  • Administrator
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  • From: Denmark
  • Registered: 2003-09-17
  • Posts: 947

Re: Artifacts in Image Analyzer display - at 1:4 and greater

You can choose between two different scaling methods in IA - in the File | Program options menu you can toggle Fast image zoom. These affect the way the images is displayed when the zoom is less than 100%

When Fast image zoom is enabled the zoom is performed by discarding pixels and when it is disabled it is done by averaging pixels taking into account the current image gamma setting.

Michael Vinther

> software developer <

admin's Website

  • Registered: 2010-05-19
  • Posts: 5

Re: Artifacts in Image Analyzer display - at 1:4 and greater

Thanks for the reply, Michael, I'll give it a try and let you know how I go.


admin wrote:

You can choose between two different scaling methods in IA - in the File | Program options menu you can toggle Fast image zoom. These affect the way the images is displayed when the zoom is less than 100%

When Fast image zoom is enabled the zoom is performed by discarding pixels and when it is disabled it is done by averaging pixels taking into account the current image gamma setting.

  • Registered: 2010-05-19
  • Posts: 5

Re: Artifacts in Image Analyzer display - at 1:4 and greater

Hi Michael, yes, de-selecting 'quick zoom' reduces the moire to a point where you can work with the image. Thanks for the tip.