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Archive 2017 · Shoot compressed or uncompressed?

Steve Spencer
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p.2 #1 · p.2 #1 · Shoot compressed or uncompressed?

JimKasson wrote:
There is no reason not to measure DR in bits. Shannon got us comfortable with fractional bits. If F is fullscale, and S is the signal plus noise at the minimum acceptable level of the signal to noise ratio, the DR in bits is log2(F/S). That is also the DR in stops.

Jim

Well there is no reason DR can't be measured in bits, but I would say there are some pretty good reasons why it makes more sense to measure it (report it) in stops. Mainly because we think about adjusting for dynamic range by using things like grad ND filters that are measured in stops. We think about using HDR with different exposures that we measure in stops. So, I think it is a lot more useful to know the dynamic range capabilities in stops than bits, but you are absolutely right that you can measure (or report) DR in bits. I am just not sure why you would.

Feb 11, 2018 at 11:28 AM

eyal
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p.2 #2 · p.2 #2 · Shoot compressed or uncompressed?

I've had the Sony a7rIII for a little over a month and had been shooting landscapes uncompressed and portraits compressed. After seeing this thread, I decided to do a more formal comparison. Shot a scene of couch with window behind. Good dynamic range to play with. Shot at iso 100.

File size:
Uncompressed RAW 85.6 MB
Compressed RAW 43.1 MB
Converting Uncompressed RAW to DNG 38 MB
Converting Compressed RAW to DNG 35.4 MB (just curious)

Comparing the images after identical settings in LR, there was a tiny bit of brighter light on the green blanket where light shone in. Also, at 100%, the coffee table edge had a bit more color and brightness in the edge facing the camera.

Scene (ignore compression artifacts):


	https://photos.smugmug.com/Forum/i-4gNGWb6/0/494c658d/S/A7R-00006358-S.jpg

Plan:
Continue shooting as I have done and consider converting to DNG later (after processing RAW and creating final TIFF in PS) if hard drive space becomes an issue.

Feb 11, 2018 at 12:41 PM

JimKasson
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p.2 #3 · p.2 #3 · Shoot compressed or uncompressed?

Steve Spencer wrote:
Well there is no reason DR can't be measured in bits, but I would say there are some pretty good reasons why it makes more sense to measure it (report it) in stops. Mainly because we think about adjusting for dynamic range by using things like grad ND filters that are measured in stops. We think about using HDR with different exposures that we measure in stops. So, I think it is a lot more useful to know the dynamic range capabilities in stops than bits, but you are absolutely right that you can measure (or report) DR in...Show more →

Among other things, it is useful to think about DR in bits and/or rms read noise in bits, when assessing if there is sufficient dither and/or sufficient precision.

Jim

Feb 11, 2018 at 01:24 PM

Steve Spencer
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p.2 #4 · p.2 #4 · Shoot compressed or uncompressed?

JimKasson wrote:
Among other things, it is useful to think about DR in bits and/or rms read noise in bits, when assessing if there is sufficient dither and/or sufficient precision.

Jim

I don't disagree, but for the photographer in the field I think it is much more useful to think of DR in photographic stops.

Feb 11, 2018 at 01:28 PM

JimKasson
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p.2 #5 · p.2 #5 · Shoot compressed or uncompressed?

Steve Spencer wrote:
I don't disagree, but for the photographer in the field, I think it is much more useful to think of DR in photographic stops.

I agree with that. For the photographer in postproduction, maybe it's not as important. But the numbers are the same, so it's easy to switch back and forth.

But I was reacting to what you said earlier -- "Color is measured in bits. Dynamic range is measured in stops." -- which I thought was overly narrow.

If you're saying that color is best measured in scalar bits, I disagree strongly with that statement, but that's a different discussion.

Jim

Feb 11, 2018 at 03:39 PM

Steve Spencer
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p.2 #6 · p.2 #6 · Shoot compressed or uncompressed?

JimKasson wrote:
I agree with that. For the photographer in postproduction, maybe it's not as important. But the numbers are the same, so it's easy to switch back and forth.

But I was reacting to what you said earlier -- "Color is measured in bits. Dynamic range is measured in stops." -- which I thought was overly narrow.

If you're saying that color is best measured in scalar bits, I disagree strongly with that statement, but that's a different discussion.

Jim

I realize that. In that post I gave an oversimple, but I thought helpful reply to another post. I still think my post was useful to help the poster sort out the issues, but your post was much more thorough and I appreciate that and I expect the other poster did as well. Cheers,

Steve

Feb 11, 2018 at 03:57 PM

lingmaaki
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p.2 #7 · p.2 #7 · Shoot compressed or uncompressed?

Picking the right level of compression depends on many factors. You should consider your needs first and foremost. If high quality images are important to your business and customers, then you should consider lossless compression. However, if your website needs to be incredibly fast, you should consider aggressive image optimization. Depending on the CMS you use, you will have certain settings to optimize to ensure that image compression remains under your full control. Do not hesitate to look into tools such as WordPress plugins to help you get the job done.

Jan 22, 2019 at 05:55 AM

Scoobert
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p.2 #8 · p.2 #8 · Shoot compressed or uncompressed?

With as huge and cheap as hard drives are I shoot everything in uncompressed.

I wont throw out anything unless I run out of space, which will never happen. It will just give me a reason to purchase a new hard drive

Jan 22, 2019 at 06:55 AM

007Boarder
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p.2 #9 · p.2 #9 · Shoot compressed or uncompressed?

I've been shooting uncompressed RAW since before Jared Polin became big on Youtube. HA!

During "normal" everyday photography I'll shoot +JPG so I can quickly transfer photos to my wife phone using the SD to Lightning cable. She enjoys quickly sharing the family photos, while I enjoy keeping the Original files.

Jan 22, 2019 at 06:37 PM

Eruditass
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p.2 #10 · p.2 #10 · Shoot compressed or uncompressed?

Interesting that there are such clear examples and diff told, but Jim Kasson says this

"November 21, 2015 at 7:23 am

I’ve read that (about the gradients), too, and have been unable to make it happen, even in simulation. When you look at the way the algorithm works, there should be plenty of photon noise dither to keep it from happening. I’m calling this an urban myth, for now."

The next comment mentions these obvious examples and a theory, but no response

https://blog.kasson.com/the-last-word/sony-a7ii-uncompressed-read-noise-and-edr/#comment-202345

mjm6 wrote:
But there are clearly-seen differences in some high contrast circumstances, even if the basic evaluations that Jim did appear to indicate that the performance is comparable.

It effectively is comparable within a range of normal microcontrast conditions, but when the contrast hits certain levels, artifacts begin to occur. Look here:

https://photographylife.com/reviews/sony-a7-ii/3

Plus, lots of places all over the web for other examples.

For normal shooting, it probably doesn't matter, but for night shooting and high contrast scenes, it might reduce the image quality somewhat if you look carefully.

Further, if you shoot for B&W processing, these artifacts may appear if you start to manipulate the...Show more →

Jan 25, 2019 at 05:15 AM

phototiimo
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p.2 #11 · p.2 #11 · Shoot compressed or uncompressed?

Sony desperately needs to add lossless compressed and small RAW options to all of their cameras. I bought the a7Riii for cropping, but I rarely need 42mp when I use the full sensor.

It would save me so much hard drive space if there was an option to downsample RAWs to 24mp and shoot compressed without needing to worry about issues when pulling shadows or highlights because of artifacts. Not to mention my buffer would clear a lot faster.

Jan 25, 2019 at 08:01 AM

chiron
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p.2 #12 · p.2 #12 · Shoot compressed or uncompressed?

Matt Grum wrote:
Unless I need to shoot in burst mode lot I shoot uncompressed now. I have plenty of memory cards and can compress the data afterwards (losslessly) if necessary. It's a small advantage, but it comes with quite a small cost (unless you are contstrained for resources).

The bottom line is that there is no effect on dynamic range when shooting compressed... but that shouldn't come as a surprise because dynamic range was never the problem with compressed RAW in the first place. The problems are with posterization.

Linear RAW is massively inefficient. Sensors are linear devices (twice the light = twice...Show more →

Very interesting and helpful explanation, Matt. Thank you.

I've got to ask--where did you acquire this knowledge? Does Sony do white papers?

Jan 25, 2019 at 08:04 AM

Holger
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p.2 #13 · p.2 #13 · Shoot compressed or uncompressed?

virtualrain wrote:
Hi, I'm curious if anyone is shooting uncompressed RAWs for the bulk of their shooting or are most people going with compressed RAWs?

On my A7RII, I shot compressed most of the time, only choosing uncompressed for evening city scape shots on a tripod. Perhaps I'll do the same on my A7RIII but I'm interested to hear what others are planning to do.

I shoot compressed at weddings all the time. Over the years now, with last year shooting around 150k images alone, I can only remember two or three images showing compression artefacts.
When ultimate IQ matters, I use uncompressed raw.
Nevertheless, I would welcome lossless raw, too.

Jan 25, 2019 at 08:46 AM

GMPhotography
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p.2 #14 · p.2 #14 · Shoot compressed or uncompressed?

I shoot both . On big jobs I will do compressed. It’s never been a issue with me.

Jan 25, 2019 at 08:55 AM

chez
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p.2 #15 · p.2 #15 · Shoot compressed or uncompressed?

Compressed for street and travel. Uncompressed for landscape. In either case, I never seen any issues.

Jan 25, 2019 at 09:10 AM

chiron
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p.2 #16 · p.2 #16 · Shoot compressed or uncompressed?

eyal wrote:

I've had the Sony a7rIII for a little over a month and had been shooting landscapes uncompressed and portraits compressed. After seeing this thread, I decided to do a more formal comparison. Shot a scene of couch with window behind. Good dynamic range to play with. Shot at iso 100.

File size:
Uncompressed RAW 85.6 MB
Compressed RAW 43.1 MB
Converting Uncompressed RAW to DNG 38 MB
Converting Compressed RAW to DNG 35.4 MB (just curious)

Comparing the images after identical settings in LR, there was a tiny bit of brighter light on the green blanket where light shone in. Also, at 100%, the coffee...Show more →

Interesting direct comparison. More of these side-by-side would be really interesting, if you wanted to do it.

Jan 26, 2019 at 08:23 AM

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