Explaination: when your image has more pixels than your screen, there are several ways to reduce its size to have it fit on screen. The naive way is to just do nearest pixel subsampling: for each pixel on screen, grab the pixel that is the closest on the image. And throw away all other pixels in the original image. This amplifies noise, or at least it does not reduce it while subsampling normally does. And it tends to give overly sharp and pixelized edges (like font rendering without antialiasing). Less naive methods include bilinear and cubic, and the most widely used high-quality algorithm is lanczos.
Gimp and Darktable obviously use a good quality resampling algorithm. Web browser started only rather recently to do so (when possible, rescaling the picture on the server is better to get full control on how it's done regardless of the browser). ----- Original Message ----- > Hi, > > I think you nailed it. I installed gimp and exported images look much > better in gimp. I'll try opening in a browser when I get a chance to see > what shows up. > > Regards, > > Niranjan > > On 08/24/2016 05:10 PM, Jason Polak wrote: > > If your exported image is being viewed at the same zoom as in the > > darkroom, can you check whether it still looks noisy in the gimp? Some > > version of image viewers on Linux don't render large resolution images > > "correctly". > > > > If it looks ok in the GIMP, then it's the image viewer's fault. > > > > On 16-08-25 09:44 AM, Niranjan Rao wrote: > >> Greetings, > >> > >> I am new to raw image development and trying to figure out what I am > >> doing wrong. > >> > >> My main problem seem to be stemming out from the fact that when I export > >> the image, it does not look like image in darkroom screen. I am trying > >> to process images generated by Canon PowerShot SX60 HS. Exported image > >> always felt more noisy or grainy. > >> > >> A little bit of experimentation and tinkering of many knobs, I figured > >> that exported image quality seems to be function of size. If I leave > >> exported size to 0, darktable exports in default size (in my case, it's > >> 4768 X 3516), exported images look grainy. If I export in smaller size - > >> say 1600, they look much nicer. > >> > >> Is this normal - having noise in default sized exported image and > >> looking cleaner in smaller image? Is there anything I can do to address > >> this issue? > >> > >> Alternatively, what would be good or usual size to export the image? I > >> am just a home user of camera and darktable, rarely print my images and > >> images are used only for viewing by family and sharing across various > >> mediums such as facebook and WhatsApp. > >> > >> I on Ubuntu 16.04, using darktable version 2.0.3 from standard ubuntu > >> repositories. I am using standard Ubuntu image viewer to view exported > >> image. > >> > >> > >> Best, > >> > >> Niranjan > >> > >> ____________________________________________________________________________ > >> > >> > >> darktable user mailing list > >> to unsubscribe send a mail to > >> darktable-user+unsubscr...@lists.darktable.org > >> > > ____________________________________________________________________________ > > > > darktable user mailing list > > to unsubscribe send a mail to > > darktable-user+unsubscr...@lists.darktable.org > > > > ____________________________________________________________________________ > darktable user mailing list > to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org > > -- Matthieu Moy http://www-verimag.imag.fr/~moy/ ____________________________________________________________________________ darktable user mailing list to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org
