# \[Raspberry Pi 5\] Banding/Dithering on Images in Chromium Kiosk
**URL:** https://dietpi.com/forum/t/raspberry-pi-5-banding-dithering-on-images-in-chromium-kiosk/20012
**Category:** Troubleshooting
**Created:** [2 May 2024 14:53 UTC](https://dietpi.com/forum/t/raspberry-pi-5-banding-dithering-on-images-in-chromium-kiosk/20012 "2024-05-02T14:53:54Z")
**Posts on this page:** 14
**Page:** 1
### Author:  [@rmscode](https://dietpi.com/forum/u/rmscode)
#### Post date: [2 May 2024 14:53 UTC](https://dietpi.com/forum/t/raspberry-pi-5-banding-dithering-on-images-in-chromium-kiosk/20012/1 "2024-05-02T14:53:54Z")
I have searched the existing open and closed issues
#### Required Information
- DietPi version | `cat /boot/dietpi/.version`
```auto
G_DIETPI_VERSION_CORE=9
G_DIETPI_VERSION_SUB=3
G_DIETPI_VERSION_RC=0
G_GITBRANCH='master'
G_GITOWNER='MichaIng'`
```
- Distro version | `bookworm 0`
- Kernel version | `Linux DietPi 6.6.20+rpt-rpi-2712 #1 SMP PREEMPT Debian 1:6.6.20-1+rpt1 (2024-03-07) aarch64 GNU/Linux`
- Architecture | `arm64`
- SBC model | `RPi 5 Model B (aarch64)`
- Power supply used | `Official`
- SD card used | `Samsung EVO`
#### Steps to reproduce
1. Fresh DietPi install
2. Install LXDE, Chromium, TigerVNC
3. Configure autostart for Chromium kiosk via `dietpi-config`. (I can’t share the URL or the images hosted on the page unfortunately)
4. Enable 4K in `/boot/config.txt` and adjust Chromium resolution in `/boot/dietpi.txt`
5. Reboot.
#### Expected behaviour
Chromium opens URL in 4k with crisp images.
#### Actual behavior
Chromium opens URL in 4k, but there is heavy banding. Especially with images containing a skyline.
#### Extra details
While having a look at Chromium in htop to see what flags it was launched with, I noticed `--enable-low-end-device-mode`. That ended up leading me to find `/etc/chromium.d`. Anyway, I wondered if any of the flags there could be causing the banding. I’ve read that flag forces 16-bit color…I didn’t think 16-bit would cause banding.
I couldn’t fiddle with the 2 RPi 5’s that were currently deployed at the time, so I pulled out an old 3B+. Ran through the entire install process as outlined above excluding the 4K configuration. In 1080P on the 3B+ there is no banding, but there is dithering. For shits and giggles, I did set Chromium to launch in 4k and it was as if I had zoomed in on one corner of the page. Coincidently, it was the corner where the slideshow was. Still no banding, just dithering. No idea what to make of that.
Edit: I’m fairly confident this is an “issue” with the Pi and/or Chromium. There is no noticeable banding (or dithering) when I open the URL on my Windows desktop.
Edit 2: Fixed some typos.
---
### Author:  [@Joulinar](https://dietpi.com/forum/u/Joulinar)
#### Post date: [3 May 2024 18:06 UTC](https://dietpi.com/forum/t/raspberry-pi-5-banding-dithering-on-images-in-chromium-kiosk/20012/2 "2024-05-03T18:06:19Z")
@MichaIng I guess the RPi5 is a little bit special on 4K. I guess it would need other settings?
---
### Author:  [@MichaIng](https://dietpi.com/forum/u/MichaIng)
#### Post date: [4 May 2024 16:28 UTC](https://dietpi.com/forum/t/raspberry-pi-5-banding-dithering-on-images-in-chromium-kiosk/20012/3 "2024-05-04T16:28:48Z")
Since RPi 3 does not support 4k, it makes sense that the viewport covers a 1080p part of Chromium, when you force it to 4k window size.
No idea in case of RPi 5. Need to find time to test myself. Does the plain console show up in 4k resolution with correct aspect ratio?
While there is some automatic detection, it is possible that you need to set it via `video` kernel command-line parameter, i.e. adding ` video=HDMI-A-1:3840x2160` to the end of `/boot/cmdline.txt`.
---
### Author:  [@rmscode](https://dietpi.com/forum/u/rmscode)
#### Post date: [6 May 2024 12:40 UTC](https://dietpi.com/forum/t/raspberry-pi-5-banding-dithering-on-images-in-chromium-kiosk/20012/4 "2024-05-06T12:40:38Z")
> [@MichaIng](#):
>
> Since RPi 3 does not support 4k, it makes sense that the viewport covers a 1080p part of Chromium, when you force it to 4k window size.
>
> No idea in case of RPi 5. Need to find time to test myself. Does the plain console show up in 4k resolution with correct aspect ratio?
>
> While there is some automatic detection, it is possible that you need to set it via `video` kernel command-line parameter, i.e. adding ` video=HDMI-A-1:3840x2160` to the end of `/boot/cmdline.txt`.
Yes. The console does show up in 4K with the correct aspect ratio.
I will try that command and report back when I have a moment.
Update: Adding `video=HDMI-A-1:3840x2160` to the end of `/boot/cmdline.txt` did not appear to make a difference in regard to the banding/dithering.
---
### Author:  [@MichaIng](https://dietpi.com/forum/u/MichaIng)
#### Post date: [6 May 2024 19:09 UTC](https://dietpi.com/forum/t/raspberry-pi-5-banding-dithering-on-images-in-chromium-kiosk/20012/5 "2024-05-06T19:09:37Z")
As this was an issue in another case, does this file exist?
```sh
ls -l /etc/X11/xorg.conf.d/02-dietpi-rpi5.conf
```
---
### Author:  [@rmscode](https://dietpi.com/forum/u/rmscode)
#### Post date: [7 May 2024 12:27 UTC](https://dietpi.com/forum/t/raspberry-pi-5-banding-dithering-on-images-in-chromium-kiosk/20012/6 "2024-05-07T12:27:57Z")
It does not.
I still haven’t had a chance to test `video=HDMI-A-1:3840x2160`, but I’ll let you know how that goes when I get to it. Also, I see that you have a 9.4 beta up. I have another RPi5 at home…I’ll try running through my same setup process on that image and see if I encounter any of the same issues.
---
### Author:  [@rmscode](https://dietpi.com/forum/u/rmscode)
#### Post date: [8 May 2024 15:37 UTC](https://dietpi.com/forum/t/raspberry-pi-5-banding-dithering-on-images-in-chromium-kiosk/20012/7 "2024-05-08T15:37:21Z")
Adding `video=HDMI-A-1:3840x2160` to the end of `/boot/cmdline.txt` did not appear to make a difference in regard to the banding/dithering.
---
### Author:  [@MichaIng](https://dietpi.com/forum/u/MichaIng)
#### Post date: [8 May 2024 19:33 UTC](https://dietpi.com/forum/t/raspberry-pi-5-banding-dithering-on-images-in-chromium-kiosk/20012/8 "2024-05-08T19:33:41Z")
Okay I am then wondering, that you have any output at all. Please try this:
```sh
mkdir -p /etc/X11/xorg.conf.d
cat << '_EOF_' > /etc/X11/xorg.conf.d/02-dietpi-rpi5.conf
Section "OutputClass"
Identifier "vc4"
MatchDriver "vc4"
Driver "modesetting"
Option "PrimaryGPU" "true"
EndSection
_EOF_
```
---
### Author:  [@rmscode](https://dietpi.com/forum/u/rmscode)
#### Post date: [8 May 2024 20:22 UTC](https://dietpi.com/forum/t/raspberry-pi-5-banding-dithering-on-images-in-chromium-kiosk/20012/9 "2024-05-08T20:22:04Z")
I can try that, but I already have a config file that tells X about the vc4 driver. It is exactly the same as what you’ve posted above, except I have named it `99-vc4.conf`. You might remember from my [other post](https://dietpi.com/forum/t/raspberry-pi-5-xorg-issues-chromium-autostart-cannot-run-in-framebuffer-mode/19963).
Does the name of the file matter?
---
### Author:  [@Joulinar](https://dietpi.com/forum/u/Joulinar)
#### Post date: [8 May 2024 21:18 UTC](https://dietpi.com/forum/t/raspberry-pi-5-banding-dithering-on-images-in-chromium-kiosk/20012/10 "2024-05-08T21:18:53Z")
> [@rmscode](#):
>
> Does the name of the file matter?
Nope
---
### Author:  [@MichaIng](https://dietpi.com/forum/u/MichaIng)
#### Post date: [8 May 2024 21:53 UTC](https://dietpi.com/forum/t/raspberry-pi-5-banding-dithering-on-images-in-chromium-kiosk/20012/11 "2024-05-08T21:53:06Z")
Ah okay, that explains that it works. I think I misinterpreted (did not lookup) the wording “banding/dithering”. The aspect ratio is the Chromium window/GUI is correct, but you have visual artefacts.
Hmm `config_hdmi_boost` (previously used to set HDMI signal strength) has not effect anymore since RPi 4. `gpu_mem` is legacy and does not have any effect on RPi 5.
Does anyone know whether `hdmi_enable_4kp60` is still needed on RPi 5 for 60 Hz? The docs say RPi 4 only, but that was probably just not updated, and it has no effect up to RPi 4.
There is a `disable_fw_kms_setup` flag to disable EDID read and HDMI config in firmware and let the kernel KMS do it instead. Can you check whether/what the firmware applied?
```sh
cat /proc/cmdline
```
---
### Author:  [@rmscode](https://dietpi.com/forum/u/rmscode)
#### Post date: [9 May 2024 15:11 UTC](https://dietpi.com/forum/t/raspberry-pi-5-banding-dithering-on-images-in-chromium-kiosk/20012/12 "2024-05-09T15:11:42Z")
```txt
reboot=w coherent_pool=1M 8250.nr_uarts=1 pci=pcie_bus_safe snd_bcm2835.enable_compat_alsa=0 snd_bcm2835.enable_hdmi=1 smsc95xx.macaddr=:13:AT:D3:AD:B3:3F vc_mem.mem_base=0x3fc00000 vc_mem.mem_size=0x40000000 root=PARTUUID=6bca6526-02 rootfstype=ext4 rootwait net.ifnames=0 logo.nologo console=ttyAMA10,115200 console=tty3 vt.global_cursor_default=0 quiet loglevel=0 splash
```
---
### Author:  [@MichaIng](https://dietpi.com/forum/u/MichaIng)
#### Post date: [9 May 2024 16:06 UTC](https://dietpi.com/forum/t/raspberry-pi-5-banding-dithering-on-images-in-chromium-kiosk/20012/13 "2024-05-09T16:06:57Z")
Hmm, either I do not understand the [docs](https://www.raspberrypi.com/documentation/computers/config_txt.html#disable_fw_kms_setup) correctly, or the firmware fails to read EDID for this LCD.
> to the Linux kernel via settings on the kernel command line
This however pretty clearly says kernel cmdline. If it hence really fails to do so, maybe the kernel is not doing so either, without this flag being set. Let’s just try it, and see whether anything is done which fixes these artefacts:
```sh
G_CONFIG_INJECT 'disable_fw_kms_setup=' 'disable_fw_kms_setup=1' /boot/config.txt
```
Ah, I should have read further:
> On Raspberry Pi 5, this parameter defaults to `1` .
However, just see whether it helps to apply it explicitly. If not, maybe the other way round 😄:
```sh
G_CONFIG_INJECT 'disable_fw_kms_setup=' 'disable_fw_kms_setup=0' /boot/config.txt
```
---
### Author:  [@system](https://dietpi.com/forum/u/system)
#### Post date: [4 November 2024 04:07 UTC](https://dietpi.com/forum/t/raspberry-pi-5-banding-dithering-on-images-in-chromium-kiosk/20012/14 "2024-11-04T04:07:26Z")
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