I'm setting this bug as "In Progress". ** Changed in: gimp (Ubuntu) Status: Triaged => In Progress
** Changed in: gimp (Ubuntu) Assignee: Ubuntu Desktop Bugs (desktop-bugs) => (unassigned) -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to gimp in Ubuntu. https://bugs.launchpad.net/bugs/16128 Title: Wide color channels in Gimp Status in The GNU Image Manipulation Program (GIMP): Fix Released Status in “gimp” package in Ubuntu: In Progress Bug description: After discussing with some graphics people in the community, it has come to my attention that Gimp only supports 8 bits per color channel (bpc), totalling 32 bits RGBA. Architecturally, Gimp is not easily expanded to wider color channels such as 16 or 32 bpc; however, it is possible. Previously, some developers created a program called "cinepaint," a Gimp fork that supported 16 and 32 bpc color spaces. Unfortunately the project eventually halted and does not support the range of features of newer Gimp. * http://cinepaint.sourceforge.net/ Although humans can't tell the difference between 8bpc and 16bpc, mathematical algorithms can. In particular, certain mathematics used to touch up images or blend colors can result in a visual artifact called "banding," where visible differences in lumance appear in the image where there previously were none, often resulting in what look like bands of areas with different gammas or brightnesses. To prevent this, the color space can be increased so that the bands occur over ranges so small that when reduced back to 8 bpc color space, they are lost with the extra information in the other 8 or 24 bits. In other words, rounding is saved for the end of the process. To achieve the best effect, images should be stored and operated on in a full range color space. Rounding down to an 8 bpc color space should only be done when the image is finally exported to a standard 24 or 32 bit format such as PNG, MNG, or JPEG. This allows the results of previous large color space operations (i.e. image effects such as blurring and glass lenses) to retain their extra information so that more effects can be added on top of them without visible artifacts, further reducing or even eliminating banding. This bug should not be a high priority, as it would require the Ubuntu developers to massively patch the internal architecture of Gimp, and then to convince the Gimp mainline developers to accept the patches. Historically, the Gimp mainline developers apparently have inverted interest in (i.e., will fight against) widened color spaces; however, professional graphics artists understand that at least 10 bpc of color space (i.e. 40 bit instead of 32) are needed to produce quality images, and hence have been moving off Gimp and onto Photoshop. Bigger is better; even high-end 3D graphics cards operate in 128 bit color (32bpc) (as noted in John Carmack's .plan file from when he was writing Doom3). To manage notifications about this bug go to: https://bugs.launchpad.net/gimp/+bug/16128/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp