Greyscale 2bit 4 Colour success with SSD1306

(Holmes) #41

This seriously disappoints me. :-/

(Jim) #42

SSD1306 cannot display a 4 colour bitmap image. It can only display 2 colours ie. black and/or white.
If however, you switch a pixel on and off continuously in sync with the frame rate, then depending on the ‘on to off’ ratio you choose, you can create the illusion of different shades off grey. The ‘on to off’ ratios are determined by the 3 black and white images which are continually swapped on screen, in sync with the frame rate.
Another way of putting is: We are PWM-ing each pixel individually.
PS: This was all your idea bateske. Have you forgotten ? LOL.

(Kevin) #43

Ah, yes I understand the persistence of vision trick to generate grays on the device. My curiosity was in using 3 images instead of down sampling to a 2 bit image format.

(Jim) #44

I’ll upload the 3 images tonight so you can see them and get a better understanding.
If you have a 4 colour bitmap sample you want me to display and upload, just post it here.

(Jim) #45

If we downsampled to 2bit we’d no longer have any grey.

Edit: I’m not thinking straight I’m afraid. Ignore the above. What I should have said was: The original image is already a 2bit (4 colour ) image.

(Kevin) #46


(Jim) #47

I’m not thinking straight I’m afraid. The original image is already a 2bit (4 colour ) image.
So what we have to do is convert this 2bit image to three 1bit (2 colour) images.

(Jim) #48

Here’s the three 1bit pics that are multiplexed on the SSD1306 display to create the 2bit greyscale colours.




Well not exactly.
256 colors usually run on a 60Hz display.
But hmm…
So say that y laptop screen flashes at some 256*60 times???
I can believe that my iPad flashes at that rate. But the computer? I can’t believe it.
Meanwhile …
@ADI8421 is being a rockstar with his rigged display as of now …
Good job dude.

out of sync

Camera refreshes @ 60. Screen @32. It’s understandable.
But from the picture it look nearly perfect.
(reveals the importance of having that line brought about to be used)

(Boti Kis) #50