Default Themes

This document lists our decisions regarding GIMP’s default theme. It can be used as a reference by frontend developers to modify our CSS files. If any part is unclear or absent, this should first be discussed within the GIMP UX tracker, then the conclusion should be written here.

This allows for consistent UI, and also makes sure that our decisions are backed by proper reasoning when relevant. Sometimes some choice may be mostly arbitrary, or even just led by taste or trends. This is fine too, yet we should not change such choice every other morning (depending on the contributing designer of the day). Keeping a stable UI is also important in order not to confuse people. Trend-based enhancements should be slow and not too frequent.

⚠️ Note that this is not a document about theming in general. This is not recommendations to third-party theme makers either. Many things in themes are personal and this is why we welcome third-party made themes for everyone to find their match. This is only about our default themes.

Limited Theming

Currently we made the choice to propose only a limited number of themes. Even though it may make sense eventually to have high-contrast themes (for accessibility, among other reasons) or a compact theme (some people prefer them when they use small displays).

We could also eventually have simply a “pretty” theme, in particular not using neutral gray colors (see the “Default” Theme / Colors section), because gray colors are kinda boring and don’t look that good compared to grayish colors with a slight tint. Yet if we decide to have only few themes, neutral gray colors should be priority because our target is advanced/high quality graphics creation (and this requires a neutral environment, especially for color works).

Rationale: limiting the workload with current number of theme contributors. When we have more contributors, we may decide to have more themes.

Sharing Code

Our current logic is to share as much code as possible between all themes and variants.

Rationale: this makes it easier to maintain all the themes and it also makes all our themes into a more consistent experience.

“System” Theme

The “System” theme is a near-empty theme, basically trying to have as few custom styling as possible, hence GIMP will display using the GTK theme currently set by default (either by your desktop, especially for GTK-based desktop platforms, or simply the default GTK theme).

We still style a few limited widgets, especially custom GIMP widgets (because these won’t be styled in a generic GTK theme), but we should never overdo it.

This theme is for people who absolutely want GIMP not to “stand out” and want homogeneous style as possible, across all software.

“Default” Theme

The “Default” theme is the exact opposite of the “System” theme in that we want to override everything we can, hence avoiding any theme leaks, i.e. decisions taken by other theme designers, which would make our interface inconsistent (i.e. different depending on the system theme).

Colors

Our Default theme must have a variant for all 3 color schemes GIMP proposes: a Dark, Light and Gray variant.

Rationale: this is indeed our main theme so if we are not even able to demonstrate all 3 variants, who will? Furthermore experience taught us that there are people appreciating, but also hating any of these variants. Somehow it’s one of these topics where you can easily find strong feelings (some people will love dark themes as much as some others will hate them; same for light and gray).

Our Default theme must only use neutral gray colors (same amount of red, green and blue, i.e. without “tint”).

Rationale: the image you work on is what you want to focus on, yet your environment actually affects your perception of colors. A few optical illusions are commonly used to explain this, such as the Checker shadow illusion (A and B are the same color):

Therefore the most neutral your user interface colors, the most trustworthy will be your choice of colors on canvas, regarding what you wanted to actually show. Since we target GIMP towards advanced users, it is important to us to provide a theme adapted for high quality color works, even though it does mean that our theme looks a bit boring. Nevertheless professionals or advanced users do not care as much as having a software which “looks boring” as they care as having a software which allow them to create artworks with the colors they have in mind.

Dark variant

The dark variant is our default color scheme.

Rationale: because of all the love/hate around theming, it often looks like there is not perfect choice here. Yet it feels like dark themes may be the ones with the less hate, especially within the creative community. Also normally the best default should be our middle gray theme but this one is probably the less kind to the eyes. So it’s a kind of compromise.

Our main colors are:

• Main Foreground color: sRGB(220, 220, 220)
• Main Background color: sRGB(60, 60, 60)

Note that we used to have a darker scheme for our dark theme (sRGB(30, 30, 30) for the background and pure white for the foreground) during development period of GIMP 3, but it was considered too dark for a range of users.

There are still some discussions around this topic as some people do still prefer a darker theme. Furthermore, some people with less eyesight may prefer higher constrast themes. Specialized themes may be created in the future.

Gray variant

Our gray variant is based on “middle gray”, so this is the most adapted theme for color works, i.e. the one which will affect the less color perception. Note however that there is no such concept as “true middle gray”, because it depends on color science research which is constantly evoluting and colors are usually chosen based on empirical experiments with test subjects (see the concept of “standard observer”), disregarding people deviating from this standard human being, even though this is statiscally not a small percentage.

Anyway as we have to choose something, we rely on color science studies, and we settled on the middle gray from the CIELAB color space, in particular with the L* (perceptual lightness) at 50%. This value of CIELAB(50, 0, 0) corresponds to sRGB(119, 119, 119). In linear sRGB, this is the value 18.42% which many photographer may have heard of.

Our main colors are therefore:

• Main Foreground color: black
• Main Background color: sRGB(119, 119, 119)

Note that the contrast is obviously lower on this theme, but we can hardly do better by definition (as our gray is supposed to be “in the middle” perceptually anyway, the full black or white are both the furthest away and perceptually at same perceptual distance).

Light variant

Our main colors are:

• Main Foreground color: black
• Main Background color: sRGB(235, 235, 235)