Re: [Gimp-user] How to prevent downsampling from bluring my image
ok. thank you for your information and i will try it. On 4/12/06, Leeuw van der, Tim <[EMAIL PROTECTED]> wrote: > Hi Steven, > > I'm by no means an expert on image manipulation. If experts recommend to > do despeckle as last step, then perhaps that might be best. > My logic was that a noisy image would be harder to scale right because > the noise could introduce more artifacts. But I could be wrong -- I > don't have that much experience, and don't have time now to do the > experiments. (Would first need to search for a suitable photo...). > However, I thought that if you already have a number of photos at hand > to experiment with, then it might be a quick experiment for you to first > reduce noise in the image, then perhaps sharpen it, and then scale it. > > > About quality of ImageMagik vs. GIMP, I have no idea. I never made a > detailed comparison of the two in quality of scaled image. > I did make a comparison of scaling of ImageMagik and PIL (Python Imaging > Library) and found them to be comparable for the photos I needed to > rescale at that point; after which I wrote my script in Python using PIL > to scale down (without any further enhancements) a full copy of all > images from my digital camera to fit my screen. But, as I said, they're > images from a digital camera and not from a scanner. And I didn't care > if a single image would come out with poor quality; it was a massive > batch operation. > At that point I had already given up on writing a GIMP script to perform > this operation in batch so I didn't compare the quality of GIMP scaling > with the others. > > > Cheers, > > --Tim > > -- woody ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
RE: [Gimp-user] How to prevent downsampling from bluring my image
Hi Steven, I'm by no means an expert on image manipulation. If experts recommend to do despeckle as last step, then perhaps that might be best. My logic was that a noisy image would be harder to scale right because the noise could introduce more artifacts. But I could be wrong -- I don't have that much experience, and don't have time now to do the experiments. (Would first need to search for a suitable photo...). However, I thought that if you already have a number of photos at hand to experiment with, then it might be a quick experiment for you to first reduce noise in the image, then perhaps sharpen it, and then scale it. About quality of ImageMagik vs. GIMP, I have no idea. I never made a detailed comparison of the two in quality of scaled image. I did make a comparison of scaling of ImageMagik and PIL (Python Imaging Library) and found them to be comparable for the photos I needed to rescale at that point; after which I wrote my script in Python using PIL to scale down (without any further enhancements) a full copy of all images from my digital camera to fit my screen. But, as I said, they're images from a digital camera and not from a scanner. And I didn't care if a single image would come out with poor quality; it was a massive batch operation. At that point I had already given up on writing a GIMP script to perform this operation in batch so I didn't compare the quality of GIMP scaling with the others. Cheers, --Tim ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
Re: [Gimp-user] How to prevent downsampling from bluring my image
On 4/12/06, Leeuw van der, Tim <[EMAIL PROTECTED]> wrote: > Hi Steven, > > Sorry that my reply is getting a bit messy but outlook on windows isn't > very well in quoting text... never mind and i thank you! > > To get the latest version depends on your distribution. You can get the > source tarball and compile, fetching any updated dependancies yourself. > But a distribution like Debian is likely to have packages already built > and available as part of 'unstable'. ok, i know how to do you. > Btw, since your images are scanned from film, perhaps they are already > somewhat noisy? yes, i found scanned images are usually noisy than digitial camera's. it is actually a pain for me. what's the best way of handling the case? > Did you try to reduce noise, or perhaps increase > sharpness / reduce blur / etc, before scaling the image? > Just a thought - but it seems to me that (down)scaling a noisy image > will give worse results than downscaling a cleaner image. i do the noise reducing using despeckle filter. but it was adviced in many other articles that tools like despeckle will also introduce blurring ( i found it's really true ) and should be down in the very final step, especially after downscaling or upscaling. so, i think i have some problem to get your point here. did you really suggest i do the despeckle or some unsharp mask things before downscaling ? > Another option would be to try scaling the images with imagemagick. It > might already have lanczos scaling and other scaling options built-in > with the version installed (or installable as pre-built package) with > your distribution. You can even write a small shell-script to scale all > images in some directory, if that's your thing. supposing my Gimp has already equiped a Lanczos interpolation, when comparing to imagemagic in scaling, which one performs better in term of quality? thanks. -- woody ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
RE: [Gimp-user] How to prevent downsampling from bluring my image
Hi Steven, Sorry that my reply is getting a bit messy but outlook on windows isn't very well in quoting text... To get the latest version depends on your distribution. You can get the source tarball and compile, fetching any updated dependancies yourself. But a distribution like Debian is likely to have packages already built and available as part of 'unstable'. Btw, since your images are scanned from film, perhaps they are already somewhat noisy? Did you try to reduce noise, or perhaps increase sharpness / reduce blur / etc, before scaling the image? Just a thought - but it seems to me that (down)scaling a noisy image will give worse results than downscaling a cleaner image. Another option would be to try scaling the images with imagemagick. It might already have lanczos scaling and other scaling options built-in with the version installed (or installable as pre-built package) with your distribution. You can even write a small shell-script to scale all images in some directory, if that's your thing. Luck, --Tim -Original Message- From: steven woody [mailto:[EMAIL PROTECTED] Sent: woensdag 12 april 2006 10:18 To: Leeuw van der, Tim Cc: gimp-user@lists.xcf.berkeley.edu Subject: Re: [Gimp-user] How to prevent downsampling from bluring my image On 4/12/06, Leeuw van der, Tim <[EMAIL PROTECTED]> wrote: > Hiya, > > What kind of interpolation do you use when rescaling the image to a > smaller size? (And what version of GIMP do you use?) i was using Linera interpolation. GIMP version seems 2.2.x on Linux > > GIMP 2.3.x added a new kind of interpolation, Lanczos I believe it's > called, which is said to work better; both for upscaling and > downscaling. Binaries of GIMP 2.3.7 are available for windows, but if > you don't use windows, then I don't know how you would best get binaries > for your platform. i think i can download source tarball and do a compile/install, right? > > Cheers, > > --Tim > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of steven > woody > Sent: woensdag 12 april 2006 10:00 > To: gimp-user@lists.xcf.berkeley.edu > Subject: [Gimp-user] How to prevent downsampling from bluring my image > > hi, > > i found any downsampling ( scale image to a smaller size ) will > definitely blur the image ( scaned from film ) to an undesired degree. > is there any suggestion around that? using a unsharp-mask after > every downsampling ? > > -- > woody > ___ > Gimp-user mailing list > Gimp-user@lists.XCF.Berkeley.EDU > https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user > -- woody ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
Re: [Gimp-user] How to prevent downsampling from bluring my image
On 4/12/06, Leeuw van der, Tim <[EMAIL PROTECTED]> wrote: > Hiya, > > What kind of interpolation do you use when rescaling the image to a > smaller size? (And what version of GIMP do you use?) i was using Linera interpolation. GIMP version seems 2.2.x on Linux > > GIMP 2.3.x added a new kind of interpolation, Lanczos I believe it's > called, which is said to work better; both for upscaling and > downscaling. Binaries of GIMP 2.3.7 are available for windows, but if > you don't use windows, then I don't know how you would best get binaries > for your platform. i think i can download source tarball and do a compile/install, right? > > Cheers, > > --Tim > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of steven > woody > Sent: woensdag 12 april 2006 10:00 > To: gimp-user@lists.xcf.berkeley.edu > Subject: [Gimp-user] How to prevent downsampling from bluring my image > > hi, > > i found any downsampling ( scale image to a smaller size ) will > definitely blur the image ( scaned from film ) to an undesired degree. > is there any suggestion around that? using a unsharp-mask after > every downsampling ? > > -- > woody > ___ > Gimp-user mailing list > Gimp-user@lists.XCF.Berkeley.EDU > https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user > -- woody ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
RE: [Gimp-user] How to prevent downsampling from bluring my image
Hiya, What kind of interpolation do you use when rescaling the image to a smaller size? (And what version of GIMP do you use?) GIMP 2.3.x added a new kind of interpolation, Lanczos I believe it's called, which is said to work better; both for upscaling and downscaling. Binaries of GIMP 2.3.7 are available for windows, but if you don't use windows, then I don't know how you would best get binaries for your platform. Cheers, --Tim -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of steven woody Sent: woensdag 12 april 2006 10:00 To: gimp-user@lists.xcf.berkeley.edu Subject: [Gimp-user] How to prevent downsampling from bluring my image hi, i found any downsampling ( scale image to a smaller size ) will definitely blur the image ( scaned from film ) to an undesired degree. is there any suggestion around that? using a unsharp-mask after every downsampling ? -- woody ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
