Halos when downsizing to .jpeg in PS

[Wally Nussbaumer]

Does anyone have an answer to this problem. It seems to make no difference if I bring a file in from RAW or straight .jpeg. I will work the file until I am satisfied and then attempt to downsize in order to post on the web. I have tried various methods that have been suggested with little success. The image looks great out of the camera (either a Canon 20D or Canon 1D MKIII) as a .tiff or .PSD the image is great. But as soon as I downsize to somewhere around 900 X 800 or less annoying halos appear. Sharpened or unsharpened they still pop up. The it takes considerable time to go through the image and manually remove them. When I expand (enlarge) the image to the point I cans see the pixels, there are white pixels around almost every dark edge....black and green seem to be the worst.
If I look very close at the .tiff, there is a very slight hint of lighter pixels when I look it pixel by pixel but in the regular sized image I am unable to see anything and they print out perfect.

[Axel Hildebrandt]

Welcome, Wally! If you save the unsharpened RAW as uncompressed TIF, downsize in Photoshop to 800 pixels, and THEN sharpen the subject only and convert to jpg, you shouldn't see any halos. Halos usually occur only when you sharpen the entire image including background or if you select outside the edges of the subject.

I hope this helps.

[Wally Nussbaumer]

Welcome, Wally! If you save the unsharpened RAW as uncompressed TIF, downsize in Photoshop to 800 pixels, and THEN sharpen the subject only and convert to jpg, you shouldn't see any halos. Halos usually occur only when you sharpen the entire image including background or if you select outside the edges of the subject.

I hope this helps.
Work flow I try to use is to open the CR2file in RAW. do any adjustments I know about there and then open copy in CS3. From there I usually do any necessary adjustments use smart sharpen as the last step before saving as a .tiff. If I am saving for the web or email I have tried every combination from downsizing the tiff before sharpening, switching to 8 bit and then sharpening, just saving for web, or save as, no difference. This is driving me nuts! Not much hair left to pull out! Do you mean I should not apply sharpening to the whole image? Tried just sharpening the bird, but that was very obvious.
:confused:

[Axel Hildebrandt]

Work flow I try to use is to open the CR2file in RAW. do any adjustments I know about there and then open copy in CS3. From there I usually do any necessary adjustments use smart sharpen as the last step before saving as a .tiff. If I am saving for the web or email I have tried every combination from downsizing the tiff before sharpening, switching to 8 bit and then sharpening, just saving for web, or save as, no difference. This is driving me nuts! Not much hair left to pull out! Do you mean I should not apply sharpening to the whole image? Tried just sharpening the bird, but that was very obvious.
:confused:

I don't sharpen the tiff file and only sharpen the jpg file after resizing it to its intended size. Yes, I don't sharpen the BG, just the subject. Sharpening the background just causes noise, which you want to avoid. Feel free to send me a RAW file by e-mail.

[david cramer]

Make sure all sharpening is turned off in RAW before you convert to tiff. Two other issues can lead to halos, or halo-like problems: contrast is too high (sometimes due to strong sunlight); or your are applying a very heavy crop. In either case, very minimal sharpening may lead to halos.

[Robert O'Toole]

Wally,

Axel is correct with the advice. I never sharpen the entire image in processing. I use a quick mask or layer mask. Fabs posted a quick tutorial a while back:
http://www.birdphotographers.net/forums/showthread.php?t=6334

Also my new Photoshop CD will cover a few selective sharpening techniques in step by step tutorials. CD should be out in a month or so hopefully :)

Robert

[Sandra Nykerk]

Also check your default algorithm for resampling and make certain it is not Bicubic Sharper. And, as mentioned before, make sure the sharpening in ACR is set for "Image Preview Only." HTH.

Sandra Nykerk