You asked in another sub-thread "what do people need >64 gigs for on a consumer desktop?" but jeff_vader started this sub-thread asking "what do you do if you are interested in >64gb workstations?"
AFAICT nobody on this sub-thread is claiming that consumer desktops should cater to our niche use cases. We're just offering examples of application domains where a high RAM-to-CPU ratio is useful.
You're right. I was following up on the "I absolutely hate how they cap maximum RAM on consumer machines" comment further up the chain but jeff_vader's question pivoted the conversation and I missed the memo. There are definitely cases where professionals need (or can greatly benefit from) >64GB workstations and I don't dispute that.
Not really. As the actual editing being added to the base image is what could push that. I think the question you'd be looking for is, "what amount of photo editing, effects, etc. would make the editing process of a 80mpix photo consume >16GB memory?"
Additionally, as for your original question: For hobby or even 'normal' professional photography, I'd guess none. But rigs like the ones used for Gmaps Street View, the recent CNN gigapixel, etc. would probably have the capability to approach that size.
I actually want to know what camera is capturing 80 megapixels at 48 bits per pixel. The IQ180 is 16 bits per pixel. Where's the camera that triples this? Or are we doing Bayer interpolation in a way that requires 48 bits per pixel for some reason? Because there definitely isn't 48 bits of actual signal there.
And yes, I also want to know what turns a 500MB photo into >16GB in memory. That's 32 full-res copies of the photo in memory. Just "a couple layers and a couple undo steps", really?
Bits per pixel: A lot of small frame SLRs (your Canons and Nikons) offer 12 or 14 bits per channel for a combined 36 or 42 bits per pixel. Medium format digital backs now offer 16 bits per channel.
Layer size: Layers add more data on top of this: alpha channel (8-16 bits/pixel), clipping mask and maybe half a dozen other things, easily bumping the whole thing from 6 to 9 or 10 bytes per pixel.
Layer count: It's fairly common to have multiple layers that are copies of the original photo, with different processing applied and blending them into the final one. I'm very much an amateur and when I'm serious about just making a photo look (not even creating something new) I end up with around 10 layers.
Undo step memory: a lot of work in the photo processing workflow is global: color correction, brightness, contrast, layer blending settings and modes, filters (including sharpening or blur) apply to every pixel of a layer. Each confirmed change (by releasing mouse button / lifting stylus / confirming dialog) is likely to have to store an undo step for entire layer.
Of course you can just persist some of that to disk, but if a single layer/undo step can be 800MB this will hurt productivity - only very recently we got drives that can write this much fast enough and that's why just a couple years ago, when having enough RAM was not really an option a lot of pro photographers had 10 or 15k RPM HDDs running in RAID0 in their workstations.
I replied about the 48 bit thing to the sibling comment. That may be how the Bayer interpolation is done so I won't argue that.
For the layers/undo steps, the "couple" of each was not my phrase. It was yours. If by "a couple" you actually meant dozens, then sure, maybe an 80 mpix photo really needs that much memory to process.
> I actually want to know what camera is capturing 80 megapixels at 48 bits per pixel. The IQ180 is 16 bits per pixel...
Presumably that's 16-bits for each channel of Red, Green, Blue. Since every pixel is composed of the three RGB components, that's how you get 48-bits for every pixel (and internally, Photoshop refers to 16-bits per color channel as 'RGB48Mode').
There aren't actually three channels per pixel on most sensors. It's one channel (and only one color) and then there's a mixing process. I'm doubtful that you need 48 bits to do that mixing correctly, but maybe that is the standard way to do it.
