I was editing a JPG image taken by Nikon D5300, a mid-range DSLR. Original picture was somewhat washed out. After some color-correction, I exported the image both in JPG and PNG format.
- Original JPG: Size = 6.6 MB
- Exported JPG: Quality = 100, Size = 16.8 MB
- Exported PNG: Size = 37.3 MB
Surprisingly, both the exported JPG as well as PNG images contain fairly visible color-grains/noise IF viewed in 'GNOME Image Viewer' on Ubuntu 14.04. The noise is NOT visible IF viewed in 'Shotwell Photo Viewer'. Such noise is not visible either inside GIMP environment or in the original image. What can the reason be?