# Schematic diagram background colour preferences

Should we have any recommendations regarding the schematic diagrams we post? In particular, I find it quite problematic to read schematics on a black background such as this one: -

Taken from here. Whereas, if I do a background fill of white it turns into what I see as a much more readable diagram: -

I have no idea if everyone feels the same because maybe it's my old eyes deteriorating but, should we have recommendations for what colour background we use in diagrams?

Does anyone have a preference? If you find both equally readable then I'd like to know because maybe I need my eyes testing and remote help amidst these covid-times is probably safer than going to the optician.

• Not so much a preference as light/dark, but more a desire for contrast. In the dark schematic, the thin dark red against black is hard to see, and the small, thin text is also hard to see against black. Your light diagram has much higher contrast, and also fits in the UI better (which helps, too!), so my preference would be for that. Policy: not sure how prescriptive I'd want to be on this, a decent schematic is rare for the most part. I think a comment to the effect of "could you make this easier to read, please" is the way to go. – awjlogan Mar 12 at 10:29
• I've always suspected that image resize works better with white background but never found anything to support my hunce. If the browser has to resize to 50% then it has to drop every second row and column and risk dropping the essential lines of the schematic above. Does anyone know if there is an optimisation going on? While we're at it, why are the LTSpice schematics so ugly? The background gives low contrast and the symbols are very poorly proportioned. – Transistor Mar 15 at 20:51
• @Transistor It doesn't look like Firefox uses a crude resample when it resizes. a test is here with a 100x100px test card displayed at 100%, 50% and 200% using the width parameter of the <img> tag and a png (so no compresion artefacts). The leftmost line is 1px in the original, pure black. At 50% it ends up as a line of 8d8d8d (141/255) and another of dcdcdc (220/255) so actually wider - but much paler – Chris H Mar 24 at 11:40
• Agree with @awjlogan that contrast is an issue regardless of color scheme. Adafruit seems to publish a lot of schematics that find their way onto this site, which have very light pink lines on white background. In order for me to read them, I need to copy them from my browser to another app. I would tell the poster to change colors, but I don't, because the schematics come directly from Adafruit. – Math Keeps Me Busy Mar 28 at 4:35
• My preference would be towards white background. – Nick Alexeev May 11 at 0:04

I don't think we could have a style even if we wanted to. The problem is there are too many users with different settings and too many programs that post schematics. For example: people post shots of spice programs, in both light and dark modes. If we required a style, then users would have to switch their settings just to post an image.

Another example: The circuit tool is in a light background mode to match the website, if they did change it to black, you'd have to update thousands of images as the schematics are converted to (png's I think) then uploaded to imgur.

I do know that some browsers support dark mode conversions, I don't think this also applies to images, but maybe there is a workaround with add-ons for browsers to convert images also.

However, if a user posts an image that is low contrast and can't be seen then it wouldn't hurt to ask them to change it to a more readable format.

• (CircuitLab developer here.) You may be able to do it without rerendering / reuploading the images. We just launched Dark Mode for our Ultimate Electronics Book textbook. (There's a Dark Mode On/Off/Auto toggle in the page footer.) We simply use a CSS filter to invert everything on the page, including the schematic images. I think it looks decent. – compumike Mar 23 at 3:23

The schematic should follow the same style as the rest of the website. Had the default theme on Stack Exchange been dark, then the first style would have been preferred (although it has really lousy contrast).

The default background color is white, so illustrations should follow the same style. This way, people who prefer a black background can still invert the whole thing and get a consistent result.

Sometimes I even try to go one step further, and make the background transparent. This was more important back when block quotes were yellowish. Here is one example.

• As a user of a dark theme I can tell you that transparent backgrounds are especially problematic, because black diagramms against a dark background a pretty hard to see ;) – jusaca Mar 16 at 9:43
• @jusaca A problem with websites in general, I'm not sure if SVG solves that – pipe Mar 16 at 10:28
• True, but while I prefer a matching dark background in diagramms with appropriate colored lines, I can see that the majority is using a bright theme. And then I think it is better to have a fixed background color in diagramms, so that readability is not effected by choice of page color. – jusaca Mar 16 at 10:37