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Author Topic: The Big Picture (ACR Super Resolution)  (Read 8171 times)

Chris Kern

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Re: The Big Picture (ACR Super Resolution)
« Reply #60 on: December 31, 2021, 07:26:32 pm »

I've been using Topaz Gigapixel for a couple of years now, and have found it quite useful on occasion (albeit less so since Adobe introduced its "super resolution" option), but it has some quirks I find disconcerting.

First, if you have Gigapixel emit a DNG, what you appear to get is not a traditional Linear DNG but the equivalent of a fully-baked TIFF in a DNG container.  Below: the respective file sizes of an RGB raw file (Fuji X-Trans), the 2X enlargement produced by Gigapixel from that raw file, and the 2X enlargement produced by Lightroom from the same raw file:

-rw-r--r--  1 ck  staff    12M Nov  9 18:35 _XT47993.RAF
-rw-r--r--  1 ck  staff   596M Dec 31 16:17 _XT47993-standard-scale-2_00x-gigapixel.dng
-rw-r--r--  1 ck  staff   163M Dec 31 16:21 _XT47993-Enhanced.dng

Although the Adobe super resolution file has been demosaiced (i.e., it's a Linear DNG), it can in some important respects be treated as a raw file—specifically for adjusting white balance and making other color corrections.  As far as I can tell—I'm no expert on this stuff, and am prepared to be proved wrong—the Gigapixel DNG is really just a fully-baked TIFF in DNG's clothing.

More irritating from my perspective is that Gigapixel appears to try to "normalize" the tone curve of any raw image it enlarges by stretching out the tonal values so they cover the full range between black and white.  That may be what the user wants, but I have not found any way to defeat this behavior and I would rather be able to control the image tones myself: when I use Gigapixel, I just want it to rebuild the image with larger linear pixel dimensions and not perform any default "editing" for me.

digitaldog

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Re: The Big Picture (ACR Super Resolution)
« Reply #61 on: December 31, 2021, 07:30:41 pm »

First, if you have Gigapixel emit a DNG, what you appear to get is not a traditional Linear DNG but the equivalent of a fully-baked TIFF in a DNG container. 
If so, that's really dumb and a bit dishonest (giving the impression it's raw simply because of the DNG wrapper). DNG is as I'm sure you know, but many do not, a cousin of TIFF and one can embed a JPEG in it. That's still a JPEG, zero advantage to having it wrapped into a DNG. I wonder how many Gigapixel users think "Wow, a DNG; I've got raw data."
A baked TIFF or JPEG is a baked TIFF or JPEG, no matter how you try to fool people.
At least Adobe is up front about what and when you end up with a Linear DNG.
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