[GH-ISSUE #48] Feature request: PNG upload #18

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sascha_hemi · 2026-03-20T17:25:57+01:00

sascha_hemi commented

2026-03-20 17:25:57 +01:00

Originally created by @jonasniesner on GitHub (May 23, 2023).
Original GitHub issue: https://github.com/OpenEPaperLink/OpenEPaperLink/issues/48

Originally assigned to: @nlimper on GitHub.

Expanding jpg2buffer to also work with PNG's would be great because jpg is not that great for compressing text and often creates unwanted artifacts

Originally created by @jonasniesner on GitHub (May 23, 2023). Original GitHub issue: https://github.com/OpenEPaperLink/OpenEPaperLink/issues/48 Originally assigned to: @nlimper on GitHub. Expanding jpg2buffer to also work with PNG's would be great because jpg is not that great for compressing text and often creates unwanted artifacts

sascha_hemi added the enhancement wontfix labels 2026-03-20 17:25:57 +01:00

sascha_hemi closed this issue

2026-03-20 17:25:57 +01:00

sascha_hemi commented

2026-03-20 17:25:58 +01:00

@nlimper commented on GitHub (May 23, 2023):

I will look into it. I think Larry made a lightweight png parse library. But having said that, if a jpeg has unwanted artifacts, it's mostly caused by bad generator software or bad settings. Even a moderately compressed jpeg containing text can be made without artifacts.

@nlimper commented on GitHub (May 23, 2023): I will look into it. I think Larry made a lightweight png parse library. But having said that, if a jpeg has unwanted artifacts, it's mostly caused by bad generator software or bad settings. Even a moderately compressed jpeg containing text can be made without artifacts.

sascha_hemi commented

2026-03-20 17:25:58 +01:00

@seeers commented on GitHub (May 27, 2023):

i also have problems with jpg, i can't get a nice output without artifacts. ( Python Image / paint )
bmp or png would certainly be better

@seeers commented on GitHub (May 27, 2023): i also have problems with jpg, i can't get a nice output without artifacts. ( Python Image / paint ) bmp or png would certainly be better

sascha_hemi commented

2026-03-20 17:25:58 +01:00

@atc1441 commented on GitHub (May 27, 2023):

As a quick fix you can save the images as monochrome bmp in paint and then save them again as jpg, the red will be gone but the image gets nice

@atc1441 commented on GitHub (May 27, 2023): As a quick fix you can save the images as monochrome bmp in paint and then save them again as jpg, the red will be gone but the image gets nice

sascha_hemi commented

2026-03-20 17:25:58 +01:00

@seeers commented on GitHub (May 27, 2023):

thank you, that works!
Now I just need to generate nice text jpgs from python

@seeers commented on GitHub (May 27, 2023): thank you, that works! Now I just need to generate nice text jpgs from python

sascha_hemi commented

2026-03-20 17:25:59 +01:00

@nlimper commented on GitHub (May 27, 2023):

I'm not a python programmer, but I asked ChatGPT nicely. After some extra convincing about my intentions, it came up with this working example.

The tricks:

create a paletted image, so the fonts are not rendered antialiassed.
save with quality="maximum" to keep the hard edges

download: jpg_demo.zip

I will add the demo to the repo.

@nlimper commented on GitHub (May 27, 2023): I'm not a python programmer, but I asked ChatGPT nicely. After some extra convincing about my intentions, it came up with this working example. The tricks: - create a paletted image, so the fonts are not rendered antialiassed. - save with quality="maximum" to keep the hard edges download: [jpg_demo.zip](https://github.com/jjwbruijn/OpenEPaperLink/files/11582895/jpg_demo.zip) I will add the demo to the repo. ![output](https://github.com/jjwbruijn/OpenEPaperLink/assets/4137036/68d2579e-b8aa-4f32-bad9-25e782690a0c)

sascha_hemi commented

2026-03-20 17:25:59 +01:00

@seeers commented on GitHub (May 27, 2023):

Sure:

from PIL import Image, ImageDraw, ImageFont

width, height = 296, 128
img = Image.new("RGB", (width, height), "white")
draw = ImageDraw.Draw(img)
font = ImageFont.truetype("arial.ttf", 35)

text_color = (0, 0, 0)
draw.text((20, height - 99), "Temperatur", font=font, fill=text_color)

temperature_text = "20°C"
text_color = (0, 0, 0)
draw.text((20, height - 60), temperature_text, font=font, fill=text_color)

img.save("temp_testimage.jpg")

@seeers commented on GitHub (May 27, 2023): Sure: ``` from PIL import Image, ImageDraw, ImageFont width, height = 296, 128 img = Image.new("RGB", (width, height), "white") draw = ImageDraw.Draw(img) font = ImageFont.truetype("arial.ttf", 35) text_color = (0, 0, 0) draw.text((20, height - 99), "Temperatur", font=font, fill=text_color) temperature_text = "20°C" text_color = (0, 0, 0) draw.text((20, height - 60), temperature_text, font=font, fill=text_color) img.save("temp_testimage.jpg") ```

sascha_hemi commented

2026-03-20 17:25:59 +01:00

@nlimper commented on GitHub (May 27, 2023):

our messages crossed, but: see above.

@nlimper commented on GitHub (May 27, 2023): our messages crossed, but: see above.