[Radiance-general] printing floating point images

[Mark Stock]

Jelle,

This is a very interesting question, and one in which I have an
interest in following. I'll share with you my limited knowledge.

It has been my knowledge from speaking and reading about display
devices (mainly reflective print and transparency film) that film
can record a greater range of brightnesses, allowing it greater
bit depth. Print is hindered by its reflective nature, and the
upper and lower bounds of reflectivity (users of Radiance are
more aware than most that what is normally percieved as white is
probably no more than 70-80% reflective).

I have been assured by professional digital printers that a
good 8-bit-per-channel image gets printed just as well as an
image with grater depth. I may have even been told that the
rasterizer upgrades the bit depth as it upsamples the image.
I can't confirm that, though.

I usually print on a Lightjet 5000. I use ra_tiff to convert my
.pic into a 16-bit-per-channel TIFF, then I use Cinepaint on
Linux to do final adjustments, outputting to an 8bpc TIFF.

Mark

On Wed, 1 Dec 2004, Jelle Feringa // EZCT / Paris wrote:

> I wonder if anyone on this list has experience in printing 32 bit floating
> point images (radiance pics preferably)? Some years ago I had some vibrant
> discussion with Iebele Abel on this matter. I find it a rather frustrating
> idea to thrash spending much time and effort getting a physically accurate
> rendered image, and thrashing a tremendous amount of image fidelity to get
> the image printed, there where it counts most. I've been able to get 16-bit
> data images, but what I'm interested in is getting the full scope.
> The relevant question indeed is what would be limiting output quality.
> Its quite likely paper of photographic means are only able to output so many
> colours. I refer to physical limitations, rather than those implied by a
> data format.
>
> It seems that film industry has successfully overcome getting lack of colour
> fidelity, also thank to the openEXR format (basically a clumsy rip-off of
> the radiance image format??) but mostly by actually being able to output the
> full scope of the data.
>
> So how would I get this done in print, its quite a concern to me.
>
> Best,
>
> Jelle.
>
>
>
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