An Impossible Case?

[jebir]

Dear fellow FourThirdsPhotographers,

I have a problem to convert an image to jpg without introducing really wierd Moiré-like artifacts. The image looks perfectly OK on the screen but after saving as jpg with PaintShopPro it gets some coloured stripes, even at the lowest possible compression.
Here is one version of the shot saved as jpg: rsz_1_P2030735.jpg .
You will easily see the coloured pattern on the silo reminding of the texture of a wooden plank.

On the other hand, if I save it as a TIFF, the Moiré doesn't show up.
Here is a TIFF version that I re-did hoping that I could avoid the effects by doing the PP differently: rsz_2_P2030735.tif . As you see, no Moiré... but good luck trying to save it as jpg...

I would be glad if anyone could tell me how to save this image as a jpg without the artifacts so that I can share it with the rest of the computerized world.


Cheers, Jens.

EDIT: In the original post, I mistaknely gave the link to the jpg version also for the TIFF image. Thanks to acme who discovered that and my apoligies to everyone who stared the whole night at the original links and couldn't understand what my problem is.

[lkeeney]

How about this? Does this work?




Lawrence

[4/3_Pickles]

Maybe I am missing something, or have tired eyes, but all them images look the same to me.

I see a lot of rainbowing colors in the golden thing.

[acme]

How about this?

I used libjpeg with 1x1,1x1,1x1 subsampling.

Btw, I think the link to your tif was this.

[KellysCayman]

Jens, I think you liked the TIF name to the jpeg.

[acme]

And just for giggles, here are your original jpeg, plus the more finely sampled version, bitwise subtracted from the tif and then multiplied by four.

Though this is pretty much a worst case example, it might be sobering to some committed jpeg only shooters.

[jebir]

Thanks everyone for giving this a thought!

Thanks to acme and Kelly who discovered that I erroneously had given the jpg-link also to the tif image and also, I'd like to apologize to everyone who stared the whole night at the original links and couldn't understand what my problem is. I feel bad since Lawrence even worked on the wrong one... sorry!

Acme, thanks for the nicely looking conversion. Your differential images clearly shows the difference. I'll see if I can make the same settings in PSP.

I do wonder though what caused the problem with this particular image? Do you have any idea?

Cheers, Jens.

[ptuk]

I do wonder though what caused the problem with this particular image? Do you have any idea?

Cheers, Jens.

Hi Jens,

I just tried converting your TIFF to a .jpg using the GIMP and got a very similar result. I think it might be an effect caused by the conversion to 8 bit colour

[acme]

Hi Jens,

I just tried converting your TIFF to a .jpg using the GIMP and got a very similar result. I think it might be an effect caused by the conversion to 8 bit colour

I tried this too, and on the default settings gimp is much better at avoiding moire than whatever produced the original jpeg. It did however substantially desaturate the image.

Here's the gimp standard settings (85%, "2x1,1x1,1x1" subsampling, no smoothing) output jpeg plus differential sample. Importantly, it's only 2/3 the size of the ideal version.

[olyinaz]

I have a problem to convert an image to jpg without introducing really wierd Moiré-like artifacts. The image looks perfectly OK on the screen but after saving as jpg with PaintShopPro it gets some coloured stripes, even at the lowest possible compression.

I would be glad if anyone could tell me how to save this image as a jpg without the artifacts so that I can share it with the rest of the computerized world.

Jens,

I noticed that there is a small amount of moire in even the tiff file, but nonetheless I think I was able to achieve a very satisfactory result (?) in PhotoShop by simply saving it as a JPEG (with a bit of compression even) after pulling the photo in as a TIFF file.

Here is my result:





The only way I could get those freaky patterns to emerge was to use sharpening or excessive compression. Let me know what you think.

Best,
Oly

[acme]

Jens,

I noticed that there is a small amount of moire in even the tiff file, but nonetheless I think I was able to achieve a very satisfactory result (?) in PhotoShop by simply saving it as a JPEG (with a bit of compression even) after pulling the photo in as a TIFF file.

Here is my result:

This image also uses 1x1,1x1,1x1 subsampling, versus 2x1,1x1,1x1 as per jebir's original jpeg. Plus it's an absolute monster; 500KB for half a megapixel!

BTW, if you want more fun with moire, try using different rescaling algorithms on the file. Aliasing sure can be a stinker.

[Henk Peter]

Your TIFF saved as jpg in PSP XI, settings standard, compression 20%, 1x1,1x1,1x1 subsampling. I could not see a difference with the TIFF compared side by side.

click the image to see the original.

Attachment 3848

[jebir]

Thanks acme, Henk, Paul, Oly, and Lawrence,

I had never played with the settings for jpg compression except for the percentage. PaintShopPro 8 has 2x1 1x1 1x1 as default and I have always used that but that is obviously not good in this case.

Does anyone have a good link to where the x x x settings are explained?

Cheers, Jens

[ptuk]

Does anyone have a good link to where the x x x settings are explained?

Hi Jens,

No idea what they mean exactly but I just tried saving in GIMP using subsampling of 1x, 1x, 1x and the moire goes away. The resultant jpg is 160KB though compared to 97KB for a standard jpg save which uses 2x, 1x, 1x subsampling.

[Sharkey]

I made this jpg with Faststone Image Viewer 2.7 Beta4 (Freeware)

Standard jpg save, 80% compression, RGB --> 283KB