If some pictures of your project were not converted properly using the function Convert pictures into JPG format, this may be due to the following reasons:
The pictures have been provided with a transparency effect or an alpha channel, respectively, which may be the case for PSD, PNG or TIF formats. Unfortunately, JPG format does not support transparency.
Pictures with a color depth of 48 bits (TIF format) are normally converted, but are reduced to a color depth of 24 bits.
See also