Guitar Photos: Strange string effect with reduced images.

This photograph is typical of the effect I'm trying to eliminate.

When the size of the photo is reduced from an original 10MB +/- JPEG to a size that I can post to the web of roughly 200kb, the strings appear to be braided. I can also see the same effect along the edges of the white pick guard.

Is there a way to fix this? The originals are fine.

What software are you using and what steps and settings are you using to resize and compress the image (jpeg quality settings)?

same issue has happened with me during sharpening of images with my guitar photos. I don't know why it happens or how to stop it. I'll be interested to hear some ideas.

thanks for posting a similar pic. Nice strat, BTW!!

dave

With these I'm just doing a quick conversion in a program called ThumbsPlus. You resize by entering one of the dimensions, in this case 1000 pixels wide and bump up the compression to a usable size.

I have CS3 and DPP, but I haven't used either for resizing.

Classic Moire artifact,.

when resizing, try fiddling with the bicubic smoother vs sharpen options...

I'd say try out both DPP and CS3 and compare. In CS3 you also have some resize "bicubic" options and many sharpening options. What you posted looks pretty severe and you should have no problem coming up with much better. It's true that a diagonal thin line when enlarged a lot will show some stair stepping but your shot is over the edge.

You are getting aliasing artifact.

Are all the strings helically wound? No single strands?

If so, it's Moiré, not jpeg artifacting. As CDS says.

Not much you can do about it - it's caused by interference patterns. It'll change if you change the angle of the strings in the picture. Experiment and you'll get the idea.

Like this: http://upload.wikimedi​a.org …e02.gif/150px-Moire02.gif

http://en.wikipedia.or​g/wiki/Moire

Try sharpening after you resize...

To reduce the frequency of the aliasing you must place the strings as parallel to the sensor pixels as possible. This is a digital artifact called stair step in some circles.

Don't use crappy software, it's that simple

sandro9mm wrote in post #10053289
Don't use crappy software, it's that simple

I doubt that...

yeah ur right but I didn't want to be rude.

Image magick resizing permits you to choose the filtering used during the resize operation, often givig better results in cases such as this. Also try sharpening very conservatively prior to resizing. Then, resize using bicubic (not bicubic sharper) then sharpen at the final size. You can also sharpen as you wish on a separate layer and paint back in the less aggressively sharpened strings.

Kirk

I used to have that same model. Loved it. Should have kept it.