Lemke Software GmbH Forum

Hi. I'm the principal developer and sole maintainer of libjpeg-turbo, which provides the TurboJPEG API that I presume GraphicConverter is using whenever users select the "TurboJPEG" option. My question is: why is there even an option for that? The options dialog says "Lossless JPEG cropping is only supported with JPEG 6c", but that isn't true. libjpeg-turbo supports lossless cropping with both the TurboJPEG and libjpeg APIs. Our implementation of the libjpeg API, in fact, supports all of the lossless transformation options that libjpeg v9d supports. The TurboJPEG API supports the most popular lossless transformation options. I'm just trying to understand what deficiencies you perceived in libjpeg-turbo that prompted you to pass this decision on to your users.

Hi,

I found no way to estimate the original used compression rate with TurboJPEG. That is currently the main reason for the option.

I need the following values for a preview of the lossless cropping:
cinfo.max_h_samp_factor;
cinfo.max_v_samp_factor;

Also, I have to use the standard JPEG code on the Apple Silicon.

Also, I have to use the standard JPEG code if the lossless codec is used.

Thorsten

@forum_adm : Any news on TurboJPEG integration in GraphicConverter on the different CPU architectures?

Is already implemented since more than 6 months for opening.

And the problems for lossless cropping and estimating compression rate?
Have you overcome these?

I just call the JPEG6 routines to estimate the compression rate - because TurboJPEG does not deliver.

Also, lossless cropping is always done with JPEG6.

Thanks for the info!