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02/19/2003 05:41:10 PM · #1 |
I've gotten a few notes that pictures I've submitted haven't been very sharp, or are soft. However upon looking at the full size originals I can not see it. I however (if looking very closly) can see softness after resizing down. I am assuming all this time I should have been using the Sharpen filter durring one or more steps.
My question is then, how should I downsize my images and sharpen them? What is the best process?
Thanks
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02/19/2003 05:47:35 PM · #2 |
Tog, the resizing process introduces the softness to the photos, which is why you cannot see it in the original. I use the unsharpen mask after I've done my processing but before adding borders (if any). Different people use slightly different workflows ... here is a good article that was posted in the tutorials.
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02/19/2003 07:43:00 PM · #3 |
| Tog, using the unsharpen mask can result in a grainy effect in the picture and shorten the depth of field if overly used.One way to resize your picture and keep quality is to increase the resolution to 300 or what ever works from the default 72, then decrease the image pixel size. This results in a sharper image! Hope this helps. |
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02/19/2003 08:22:41 PM · #4 |
Originally posted by Dim7:
One way to resize your picture and keep quality is to increase the resolution to 300 or what ever works from the default 72, then decrease the image pixel size. This results in a sharper image! Hope this helps. |
Actually that's not true at all. Changing the resolution does nothing to an image when viewed on a monitor. This number only means something when printing. And tog, the way to do it is what franziska said. Sharpen last.
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02/19/2003 09:28:58 PM · #5 |
I experienced that the interpolation type can influence the sharpness very much when scling down. E.g. my image editor (The Gimp) has the options Nearest Neighbor, Linear, Cubic (goto File->Preferences->Environment) but I guess others have similar options. Nearest Neighbor seems to just drop every x rows/columns of pixels while the other two try to do some antialiasing or subpixeling. This makes them smoother and (at least subjectively to my eye) lose detail.
It depends on the photo, whether I use either the one or the other method. Sometimes (e.g. landscape photos) Nearest Neighbor is better and sometimes Linear/Cubic (e.g. on photos whith striking lines).
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02/19/2003 09:49:41 PM · #6 |
â€Â¢Always use Bi-Cubic resampling method (or non-Photoshop equivalent).
â€Â¢Always sharpen as the last step (before borders) using the Unsharp Mask filter. It is sometimes advisable to apply the filter with lower settings twice than with larger values once.
â€Â¢Set the Threshhold value higher if you have smooth gradients or flesh-tones to avoid banding effects.
â€Â¢Unsharp Mask can sometimes be used to extreme excess for "artistic" effect; see this example. |
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02/19/2003 10:04:02 PM · #7 |
actually, i found a situation recently where photoshop was just plain failing at resizing down an image.. it was leaving what you call "moiré" patterns (because of a fine pattern in the image). I found the solution with Irfanview ( //www.irfanview.com ) which offers 6 different resize sampling filters, the best one being the Lanczos filter. I dont know how, but it resized the pic that photoshop just couldn't.
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02/19/2003 10:15:59 PM · #8 |
Three approaches to dealing with moire:
1-Resample in multiple stages instead of all at once if it's a sizable reduction.
2-Rotate the image 15 degrees before resampling. Afterwards rotate back and crop the excess.
3-Apply slight blur to the photo or make a mask for just the problem area. This is roughly the equivalent of "de-screening" a halftone derived from a previously printed piece.
I guess you could see if one of Photoshop's non-recommended algorithms works better in this case. But certainly using IrfanView is great if it does the job -- I use it frequently as a viewer and to extract EXIF, and I've re-sized a few images when I needed them quickly for email or something and had no problems...it's very handy, fast, and free. |
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02/19/2003 11:50:56 PM · #9 |
My thanks to all of you, I will try all the suggestions and get back to you. I tried unsharp mask and was pleased with the results. It really did look clearer.
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