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NautiluX / slide

Simple slideshow showing random images from specified directory
MIT License
105 stars 19 forks source link

Artifactual image display #26

Closed Oberloewe closed 3 years ago

Oberloewe commented 3 years ago

When I start the slideshow, the displayed JPG images appear in a very poor quality. There are artifacts (e.g. when images with roofs are displayed) and on closer inspection it seems that there is no antialiasing. When I view the JPG images in the desktop environment with the default viewer, the image also appears in poor quality, but only for a very short time (about 1 second). After that, the images are displayed in the expected quality. I am using a Raspberry Pi 3B running Raspbian Buster with LXDE desktop environment.

Since I' m new to the topic, unfortunately I don't know if my problem is due to a wrong setting of Slide or if it's a wrong setting of the OS.

NautiluX commented 3 years ago

Can you probably provide an example source image along screenshots with slide and the system preview software so I can try to reproduce the issue?

Oberloewe commented 3 years ago

Hi. Here are two photos of the same picture (I took them with my smartphone). You can see the displayed artifacts best on the houses rooftops. I use a PI 3 with the latest Respberry OS (Desktop) and the images are located on a USB flash drive. The display is a HD ready TV with 720p. If I use FEH to watch the images the artifactical effect can also be seen but approx. just for 1-2 seconds depending on the file size. It seems like the picture is displayed in a low quality first and after doing some post calculations the quality is rised. But if I use SLIDE the images are displayed in the low quality and reside in this low quality. I can see this behavior with all JPG pictures.

IMG_20210124_203328 IMG_20210124_202146

NautiluX commented 3 years ago

what's the image size of the original picture?

NautiluX commented 3 years ago

Are you able to build the project yourself and modify a bit of the code? If so, could you try if changing the transformation mode in the call of the scaled function here from Qt::FastTransformation(the default) to Qt::SmoothTransformation helps with your issue (and create a PR if so)?

Oberloewe commented 3 years ago

I attached the original image, but the size does not really matter. I already tried a comprimised version of the image as well as other images. Unfortunately I have never built such a project from the sources...

Luftbild

NautiluX commented 3 years ago

I'll try to add it as option, so you can try it out. Guess it'll use more resources to do the smooth scaling.

NautiluX commented 3 years ago

Please try release 0.9.7. I changed scaling to smooth by default, since it performs well on Raspberry Pi 3 as well as the Raspberry Pi zero.

Oberloewe commented 3 years ago

I tried the latest 0.9.8 release and its working perfectly now. Many thanks for your efforts.