Wallpaper limitations and optimization for Raspberry Pi devices

[Joystick2600]

I have a Raspberry Pi 4 4 Gb version thats running Lakka OS 3.3 for this subject. My default TV/monitor is a 1080p 16:19 aspect ratio. A few times I have connected it to a 4K TV.

I’ve tried images found in a variety of file sizes, colors and resolution sizes. What I don’t know is what exactly is the limit and what works really good.

In my experiences jpeg images behaved poorly and showed glowing pixels, which prompted me to converting some of them into a png format. Some of the complex artworks make it harder to read the text, though you can improve it by changing the font color and the font itself. Minimalist and simple backgrounds tend to work better for Lakka OS.

I’ve tried some images that are vertical and they seem to be kinda compressed down which makes them look a bit funny. I was messing around with a huge resolution of 5000 x 3268 and a file size of 14 Mb only for it to display black and not even appear in the image preview for selecting wallpapers, same thing happened with another image of 45000 x 3250 and a 6.2 Mb size.

I’ve seen some images that are really long horizontal resolution but a small vertical resolution which makes them pretty skinny images but I have not tested them out to see if they worked out fine. Another example of an image would be those that are even in size ie 1000 x 1000. If I do get around to it and test things out I will try to update this.

As for the Raspberry Pi 4 what resolution is the GUI set to? I’ve used some higher resolution images and they seem to be fine. What happens to a image that is a little too small is it stretched? How does Lakka OS interact with wallpapers?

This post is mostly for reference, since someone else would probably want to use their favorite images as a background. Some of the background images I’ve used are not wallpaper but I just use them as such anyway. Some fonts I’ve used that are bolder and bigger in size help the menu being more readable in some backgrounds, IE Coconutz,GilaBold.

Raspberry Pi 4 specs

Sources:

• Font Space For free Fonts
• Konachan.net Anime/Japanese video games wallpaper
• Yande.re

[metchebe]

Hi. Your question is kind of confusing but I’ll try to answer:

1. The GUI resolution is the same as the display resolution. I understand that Lakka on RPi4 is limited to 1080p even on 4K TVs for performance reasons, although I could be wrong. I don’t have an RPi4 to verify this.
2. If you use an image that has a different resolution it will scale it up or down. As far as I can tell it is done with a simple bilinear filter.
3. For best quality it should be better (but perhaps not really noticeable) to use an image that matches the display resolution, in your case 1920x1080. Using a bigger image is unnecessary, using a smaller one will make it look blurry depending on the amount of scaling required. You can crop and/or resize an image with the filters you want to make it look exactly as you want
4. I’ve only used PNGs so I can’t comment on if it looks better than JPG but since PNG is lossless you won’t lose quality if you edit or create images yourself.

[Joystick2600]

My post was part question and also part reference, so that another user can use this info. So I tested some images and found that some of them that were not quite desktop resolutions were stretched a bit.

The Rapsberry Pi 4 has support for 4K, but I don’t know if Lakka OS displays 4K resolutions for the GUI when it comes to the Raspberry Pi 4.

As an example I think this one was stretched a bit vertically. Its dimension 1088 x 699, png image format. I’ve rotated the original image so I can use it as a background.

Example when using Jpeg images on Raspberry Pi Devices running Lakka OS, some of them are really bad with pixels not rendering correctly. As you can see by the miss-colored pixels in this image are a blueish glow

Same Image but converted to PNG. 1044 x 1044 image it appears to be squeezed down a bit when set as a background/wallpaper. The original image