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#1
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JPG > Crop > Save > Degrade?
In graphics programs like PhotoShop (I'm using v 8 cs), the general
advice is to interim-save in the app's native file format while working on a image. If you repeatedly save in JPG, the image degrades with each save. I understand that saving in PNG doesn't degrade the image since it's lossless, but you may lose something important to your work, like layers. But what if you start with a JPG and then just crop it? Does the save at maximum quality just save the exact data from the cropped part, or does it resample and save, thus degrading? What about other apps? MS Office picture manager and Paint Shop Pro? What happens when you crop and save in those? -- ********************* * Nehmo Sergheyev * ********************* |
#2
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JPG > Crop > Save > Degrade?
Nehmo Sergheyev,
When working in Photo Shop, Digital Image Suite, Paint Shop, Photo Draw or any editing software, we always save in the native format unitl ready to publish then save to jpg. This way we always have the native file format if needed for re-edit.... |
#3
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JPG > Crop > Save > Degrade?
On Tue, 11 May 2004 19:48:53 -0500, "Nehmo Sergheyev"
wrote: In graphics programs like PhotoShop (I'm using v 8 cs), the general advice is to interim-save in the app's native file format while working on a image. If you repeatedly save in JPG, the image degrades with each save. I understand that saving in PNG doesn't degrade the image since it's lossless, but you may lose something important to your work, like layers. But what if you start with a JPG and then just crop it? Does the save at maximum quality just save the exact data from the cropped part, or does it resample and save, thus degrading? What about other apps? MS Office picture manager and Paint Shop Pro? What happens when you crop and save in those? It doesn't matter what app you use. Anytime you do anything other than just open a jpg i.e. anytime you actually do something to the file, and then resave it, image quality is degraded. Maximum quality doesn't mean retention of all pixels, it just means the best you can get given that the image will be downsampled. -- Hecate veni, vidi, reliqui |
#4
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JPG > Crop > Save > Degrade?
Precisely the reason that you should have more than one original copy of the file to be edited then published.
When finished, you can use one from your folder/backup to apply the final edits to.... |
#5
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JPG > Crop > Save > Degrade?
On Tue, 11 May 2004 19:48:53 -0500, "Nehmo Sergheyev"
wrote: In graphics programs like PhotoShop (I'm using v 8 cs), the general advice is to interim-save in the app's native file format while working on a image. If you repeatedly save in JPG, the image degrades with each save. I understand that saving in PNG doesn't degrade the image since it's lossless, but you may lose something important to your work, like layers. But what if you start with a JPG and then just crop it? Does the save at maximum quality just save the exact data from the cropped part, or does it resample and save, thus degrading? What about other apps? MS Office picture manager and Paint Shop Pro? What happens when you crop and save in those? Whenever cropping requires the image to be decoded into a pixelmap and re-encoded in JPG-blocks there is a chance of degradation. If the cropping occurs without decoding along the borders of existing 8x8 pixel JPG-blocks ("Lossless cropping") there is no degradation beyond the existing image condition. Michael |
#6
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JPG > Crop > Save > Degrade?
- Kris Zaklika -
Take a look at Guido Vollbeding's Jpegcrop (http://jpegclub.org/) - Nehmo - According to the site, 'lossless' cropping of JPEG images' if you use (free) jpegcrop for Windows. I've been opening my photos in MS Office Picture Manager (It opens quickly), where I do the initial crop. I'm now thinking that's a mistake (if it resamples than saves). I should initially open with jpegcrop. Then later when I want to edit, in PSP or PS. -- ********************* * Nehmo Sergheyev * ********************* |
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