Hi how do i make a lossless/uncompressed output of a "picture slideshow clip"

like when importing 500 frames as a picture slideshow where each frame length is 00.00:01 long.

Then I want to export it to a uncompressed file which i can compress with another program as I like.

Lossless export is experimental and therefore very few softwares are able to read this export. The only lossless export format which really works now is SNOW from ffmpeg project. To preserve a high quality, I would rather invite you to use the h264 codec at a high rate. Also, make sure to use Kdenlive 0.7. Older versions are deprecated. Kind regards, Jean-Michel