Epub export randomly converts jpg to png

[grhanka]

When exporting to EPUB, with the image-conversion rule set to, "Auto", Indesign converts some JPG images to PNG, drastically increasing the file size.

I can't predict which JPG images will be converted to PNG. The choice bears no obvious relation to layer, overlaying text, resolution, or size.

If I set the image-conversion rule to, "JPG", I lose the transparency of my PNG images. They all get a white background.

If I set the image-conversion rule to, "Use original format", my images aren't downsampled, and again the file is huge. Manual downsampling is not practical, because epub requires 150 dpi, while print requires 300.

Help.

[Steve Werner]

Moving to InDesign EPUB forum

[John Mensinger]

grhanka  wrote

Manual downsampling is not practical, because epub requires 150 dpi, while print requires 300.

Naw, print doesn't require 300 ppi. If one file really has to be dual-purpose, find a compromise (somewhere around 180-200 ppi) and manually downsample.

[grhanka]

Another clue: If I delete the JPG and re-place it, then it stops converting to PNG. Maybe I placed them wrong, but I don't know how.