| Author | Thread |
|
|
10/01/2004 04:55:33 AM · #1 |
I found this:
//www.angelo.dsl.pipex.com/Resizing/
It seems to me to be able to produce some nice results better than using the 10% stairway steps method.
Message edited by Manic - url-ifying. |
|
|
|
10/01/2004 05:34:23 AM · #2 |
| Results are impressive, but it's done in PNG format (does anyone use that format anymore?). I wonder if the same results could be had using JPEG. |
|
|
|
10/01/2004 05:37:17 AM · #3 |
PNG is newer than JPEG and GIF, I think. I believe PNG was promoted for adoption because of the ludicrous GIF licensing (which even a spokesperson of Unisys said they didn't understand).
Message edited by author 2004-10-01 05:37:33. |
|
|
|
10/01/2004 05:41:39 AM · #4 |
PNG is actally quite a bit more advanced than GIF. It's losseless and has support for alpha channels and more than 256 colors. The only reason it isn't in wide use is that IE is pretty braindead in its support for it, almost completely nullifying its advantages over GIF.
As to your question, the method should work very similarly with jpeg, provided the jpeg doesn't have nasty artifacts in it. Whether this technique is useful for anything other than whole number multipliers is another question entirely.
|
|
|
|
10/01/2004 06:03:13 AM · #5 |
| So I would have to first convert from a TIFF or JPEG to PNG and then after the resizing back to JPEG again? Doesn't that result in lower quality images and introduce compression artifacts? Or is this result to stay in PNG? |
|
|
|
10/01/2004 06:08:31 AM · #6 |
Anytime you convert a photo to a jpeg, you create compression artifacts. TIFF (I believe) is a lossless compression algorithm, as is PNG. So that means whatever you put in to these formats, you get back out.
ie. Converting from PNG->JPG will reduce the quality of the original PNG.
Converting from JPG->PNG will retain the same image quality as the original JPG.
Make sense?
You don't have to convert to PNG to use this technique, btw. It will work the same on JPG. |
|
|
|
10/01/2004 06:12:37 AM · #7 |
Originally posted by mbardeen:
Anytime you convert a photo to a jpeg, you create compression artifacts. TIFF (I believe) is a lossless compression algorithm, as is PNG. So that means whatever you put in to these formats, you get back out.
ie. Converting from PNG->JPG will reduce the quality of the original PNG.
Converting from JPG->PNG will retain the same image quality as the original JPG.
Make sense?
You don't have to convert to PNG to use this technique, btw. It will work the same on JPG. |
Thanks, got it now. |
|
|
|
10/01/2004 06:15:39 AM · #8 |
The loss of data happens when one reopens a jpg image. Working on a jpg or tiff or png will all work the same, as far as I know. I change to Lab Color a lot, and so change the file automatically to a Photoshop file.
As far as resizing, I usually just set my crop tool to 20 in. by 16 in. by 150 px/inch and crop. I've looked very closely and can't find much difference. In fact, I sometimes get better results with this one step method.
After cropping, I'll often apply a slight Dust & Scratches or Smart Blur to get rid of weird things, or just blur the A and B channels in Lab Color to get rid of color noise.
|
|
|
|
10/01/2004 06:25:06 AM · #9 |
Originally posted by dsidwell:
The loss of data happens when one reopens a jpg image.
|
Actually, it's on saving the image where the data loss occurs. So if you save as jpg then close the image, all you have left is the lossy jpg (Which is why it appears as the loss occurs on reopening).
Once you have the file open, no further data loss *should* occur until you close that file.
I say *should* because I'm not sure if all image editing programs work the same. Certainly the better ones (Photoshop, The GIMP, Paintshop Pro) will not lose data.
|
|
|
|
10/01/2004 02:45:47 PM · #10 |
Originally posted by mbardeen:
Originally posted by dsidwell:
The loss of data happens when one reopens a jpg image.
|
Actually, it's on saving the image where the data loss occurs. So if you save as jpg then close the image, all you have left is the lossy jpg (Which is why it appears as the loss occurs on reopening).
Once you have the file open, no further data loss *should* occur until you close that file.
I say *should* because I'm not sure if all image editing programs work the same. Certainly the better ones (Photoshop, The GIMP, Paintshop Pro) will not lose data. |
Even closing the file doesn't matter -- just saving it. jpg, gif, png and the others are storage formats; some lossy, some not -- they have nothing to do with the data loss from editing.
David
|
|
|
|
10/01/2004 02:50:16 PM · #11 |
Originally posted by dsidwell:
... As far as resizing, I usually just set my crop tool to 20 in. by 16 in. by 150 px/inch and crop. I've looked very closely and can't find much difference. In fact, I sometimes get better results with this one step method.
After cropping, I'll often apply a slight Dust & Scratches or Smart Blur to get rid of weird things, or just blur the A and B channels in Lab Color to get rid of color noise. |
So you resize the image before you edit it? or do you do all of your editing on the full image and then crop?
Sorry if this is heading a bit off-topic, but is quite different from most workflows I've seen where the crop is before editing and resizing after.
David
|
|
Home -
Challenges -
Community -
League -
Photos -
Cameras -
Lenses -
Learn -
Help -
Terms of Use -
Privacy -
Top ^
DPChallenge, and website content and design, Copyright © 2001-2025 Challenging Technologies, LLC.
All digital photo copyrights belong to the photographers and may not be used without permission.
Current Server Time: 09/12/2025 07:09:29 PM EDT.
