A question about Silverfast HDR


So RT will be my first ever photo editing software. And I would like to express my admiration to all the contributors giving their time to make RT a reality.

I am scanning negatives with a V800 using Silverfast (Negafix is a lifesaver).

In Silverfast, I can scan in TIFF or DNG :

  • TIFF 48 > 24 bits where I can edit the image (iSRD, Negafix, etc.)
  • HDR 16 or 48 bits TIFF or DNG with some image editing
  • HDRi 32 ot 64 bits TIFF or DNG with some image editing.

I understand that with TIFF 48 >24 bits, all the editing will be “baked in” the image, where HDR/HDRi the editing is saved in the TIFF file for later modification (non destructive editing process). Also, with HDRi, the infrared channel is saved. But then, is seems that HDR(i) is a format for their HDR software family.

My questions : does RT read the HDR TIFF format from Silverfast? Or, to put things in another perspective : is there an advantage to scan in HDR 48 bits TIFF instead of 48>24 bit TIFF ? I guess that RT does not read the infrared channel (no tools to use it) - no need for HDRi.

I understand that RT 5.8 does not recognize DNGs coming out of a scanner (will / should be the case in 5.9 with negative inversion of TIFF/DNG). In other words, should I worry about TIFF when DNG is available ? Is there any advantages of DNG over TIFF ?

Thank you for your time.

I do not have answers to your question, but I will be following this post with interest as I have an Epson V850 and I find both the Epson and the Silverfast software really disappointing. Previously I had a Canon 9000F for scanning the film and the software was much nicer and produced good scans capturing the highlights and the shadows. Currently when scanning negatives I scan as positive and use negadoctor in Darktable to invert and fix the image.

@Terry VueScan is where its at.

Thanks for the suggestion. I have tried vuescan and it didn’t cut the mustard for me either. Strangely enough or maybe not, the canon software was the best. Shame the scanner stopped working.

I am also following this post with interest because I did a lot of scans both from negative and from dia using an old epson 4870 and a newer epson V600. The old 4870 is much better but also a lot slower. I with the epson software, using properly curves and adjustment layers, I have always obtained quite satisfactory results. Much less with Vuescan who disappointed me deeply. Silverfast was once given with the 4870 in the Se version: unfortunately the version I have no longer works with win 10 so I can no longer use it. I have tried to scan and treat the file with rt but I find it impractical and the results quite mediocre.

It will recognize what is known as “linear DNG”, however the negative inversion module doesn’t work with such DNGs in 5.8 - I believe this is fixed in dev builds.

DNG is just TIFF with additional metadata

The HDR-formats in SilverFast are just normal TIFs with 3 images (or DNG, see above) but they are linear scans, i.e. without gamma-correction and without any image processing applied. So it is not a proprietary format! The IR-channel is just the third image in this set of 3 (RGB-scan full resolution, preview scan, IR image). However, there is no software around which can use the IR-channel to correct for dust and scratches except for SilverFast HDR (and if you use VueScan, the IR-channel is the 4. channel with each pixel holding 4 values: R, G, B, IR. You have to use VueScan to make use of the IR-channel in this case).

If you use RT for the HDR-images they appear very dark due to the lacking gamma-correction. You should either apply the gamma-correction before opening the image by another software or - better - use an ICC-profile which has the gamma-correction incorporated, i.e. being derived from a target scan in HDR-format.


So, if I got this right…

The HDR format is a 48 bit TIFF that has additional information for Silverfast software. But since it is primarily a TIFF, then Rawtherapee is able to read 3X16 bits and all the other basic information of a TIFF. The other informations are just not read by RT.

If I recall, in Silverfast, I can scan in HDR-48 bits, apply “negafix” and save in TIFF instead of DNG : this gives a positive with the appropriate “color balance”.

Is it worth it — more flexibility in RT? — to scan in 48 bits when monitors are (all?) 24 bits ?


Definitively, if you are going to do some image processing. 8bits/channel is at the limit of what the eye can discriminate. So if you work on the image and loose some depth, you will see this in the result. So go with 16bit/channel in TIF and at the very end convert to JPG with 8bit/channel.