Loosing definition when scanning HDR

[nhatphongtran]

Hi!

I just bought SilverFast8 SE with a Plustek 8200i film scanner and had issues with HDR scanning.
So it looks like scanning a multi-exposure HDR at 16bits/channel has less tonal definition than without HDR scanning. When I compare a 8bit/channel scan to an HDR scan, the HDR has all data in its histogram all the way to the right and when I set the black levels to start at the first sets of data - thus compressing the histogram - all gradients in the image look very steppy compared to the 8bit scan. This operation was done in Photoshop in 16bit entirely. So is this a bug? I’d expect the software to spread the data through all bits of the image and not only all the way at the upper end. I'm using SilverFast8 on OSX 10.9 with Photoshop CC.

Thanks a lot!


Nhat

[LSI_Ketelhohn]

Dear Nhat,

The 16/32/48/64 bit HDR(i) formats are archive formats.
These are stored unchanged for later processing in SilverFast HDR (Studio).

When openeing the images in another software make sure they are handled correctly.
Photoshop must be set up to use the embedded colorspace.
It will not do that automatically, because the embedded colorspace is the device color space of the scanner and not a working space.
Current Photoshops could assume sRGB if not set up correctly which of cause will compress the colors.
Also the images are stored at a gamma of 1.0.

Generally it is suggested to use the normal 48 Bit or 48->24 Bit outputs for later processing in Photoshop.
This makes sure the colorspace has been rendered.
For this to be done correctly it is important to set the highlights and shadows in SilverFast.
Not doing so can result in a loss of dynamic range.

kind regards,
Arne Ketelhohn.