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Author Topic: When do adjustment brush changes occur?  (Read 17285 times)
slc
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« on: February 01, 2009, 04:21:48 PM »
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My workflow involves opening and editing in ACR, then moving to Photoshop for more editing. I know that many adjustments in ACR, especially exposure, curves etc., occur early in the image conversion process as part of gamma correction or thereabouts. This means you get a better quality result by making those corrections in ACR rather than waiting until you are in Photoshop.

Does one get the same benefits from adjustment brush corrections in ACR as one does from making exposure corrections, or are adjustment brush corrections made after the RAW file has been converted to a viewable image?

Or more generally, which corrections made using the new ACR 5 features are applied early in the conversion process?

  - slc (a new member of Luminous Landscape forums)
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pegelli
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« Reply #1 on: February 12, 2009, 08:21:16 AM »
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I would say yes, as any "instruction" to modify is applied to the original linear raw data which should in the end be more accurate than applying it to the gamma/log converted data that you work with in PS. If someone knows better pls. chime in. I'm not a specialist and trying to apply "common sense" which is dangerous.

Second big advantage is that it is non destructive with very little file size increase. In PS it's either a permanent "not undoable" change or a large file size increase with every operations saved in it's own layer.

So in my own workflow I try to use PS as little as I can away with and do everything in LR (which is virtually the same as with ACR)
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pieter, aka pegelli
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« Reply #2 on: February 12, 2009, 11:39:29 AM »
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Quote from: slc
Does one get the same benefits from adjustment brush corrections in ACR as one does from making exposure corrections, or are adjustment brush corrections made after the RAW file has been converted to a viewable image?

Or more generally, which corrections made using the new ACR 5 features are applied early in the conversion process?


Uh huh...ya know, you REALLY don't need to worry about that. The Camera Raw processing pipeline is optimized by the engineers and they know enough to do the "right thing" in terms of when in the pipeline a process will be done, ya know? Unless you want to get into writing a raw processing apps, you really don't need to worry about which stage what step is done (and the odds are, the engineers won't be too forthcoming anyway).

If you want a real programming guide to the pipeline, I suggest downloading and reading the DNG SDK (not, to make sense, you'll need to know code).

As far as when and where you "should" be doing various image adjustments, do them in the location where the task is most easily handled. Figure on doing the vast majority of the image adjustments in Camera Raw and the remaining in Photoshop if you need pixel level manipulation.
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Wayne Fox
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« Reply #3 on: February 12, 2009, 04:32:20 PM »
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I guess the reason for the OP's question might be if all ACR is doing is rendering a tiff file, then applying adjustments, then sending that modified tiff file to Photoshop the only real advantage might be convenience.  (Someone said Aperture does some "adjustments" but in reality this is how it works.)

I do not believe LR/ACR works this way however, the adjustments are part of the RAW rendering process (someone correct me if I'm wrong).

As long as this is occurring as part of the rendering process, and not just post rendered/pre PS, then I agree with Jeff ... I'll trust the engineers on just where and how they are actually including those adjustments.  My guess is it depends on the adjustment itself.  All I know is they are terrific tools, and I can't live without them now.
« Last Edit: February 12, 2009, 04:32:52 PM by Wayne Fox » Logged

slc
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« Reply #4 on: February 13, 2009, 11:58:12 AM »
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Quote from: Wayne Fox
I guess the reason for the OP's question might be if all ACR is doing is rendering a tiff file, then applying adjustments, then sending that modified tiff file to Photoshop the only real advantage might be convenience.  (Someone said Aperture does some "adjustments" but in reality this is how it works.)

I do not believe LR/ACR works this way however, the adjustments are part of the RAW rendering process (someone correct me if I'm wrong).

As long as this is occurring as part of the rendering process, and not just post rendered/pre PS, then I agree with Jeff ... I'll trust the engineers on just where and how they are actually including those adjustments.  My guess is it depends on the adjustment itself.  All I know is they are terrific tools, and I can't live without them now.

I'm the OP. I know that global adjustments are made during rendering. I was asking if local adjustments are also made during rendering, or if they are made after rendering like they would be in Photoshop?

I'm lazy, I would like to receive a canned answer from someone who already knows rather than reading the SDK....

  - slc
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digitaldog
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« Reply #5 on: February 13, 2009, 12:08:33 PM »
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Quote from: Wayne Fox
I guess the reason for the OP's question might be if all ACR is doing is rendering a tiff file, then applying adjustments, then sending that modified tiff file to Photoshop the only real advantage might be convenience.  (Someone said Aperture does some "adjustments" but in reality this is how it works.)

That's not what its doing. But you're right to point this out as many Raw converters and some 3rd party plug-in's give the impression they are working in the Raw pipeline when in fact, they are simply handing off a rendered image. That's no better than doing the same work in Photoshop albeit, maybe faster and negating the need to have Photoshop. As you point out, that's exactly what Aperture is doing.
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Andrew Rodney
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« Reply #6 on: February 13, 2009, 12:57:36 PM »
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Quote from: slc
I was asking if local adjustments are also made during rendering

More or less (your terminology doesn't lend itself to a yes answer).

All of the luminosity adjustments are a concatenation as are all the color adjustments and then the stuff is put together just before the color space transform into the output space.

So, yes, do it in raw if you can...
« Last Edit: February 13, 2009, 09:05:37 PM by Schewe » Logged
madmanchan
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« Reply #7 on: February 13, 2009, 05:22:04 PM »
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slc, there is a single Camera Raw rendering pipeline, and both CR's global and local adjustments are performed as part of that rendering pipeline.
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Schewe
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« Reply #8 on: February 13, 2009, 09:09:30 PM »
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Yeah, what Eric said...

Do what you can do easily in Camera Raw (or Lightroom) and do everything else in Photoshop (if you must). It's really not that hard to figure out. Parametric vs. Pixel Editing...use the tool that best handles the task at hand.
« Last Edit: February 13, 2009, 09:10:03 PM by Schewe » Logged
slc
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« Reply #9 on: February 14, 2009, 11:43:05 AM »
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Quote from: madmanchan
slc, there is a single Camera Raw rendering pipeline, and both CR's global and local adjustments are performed as part of that rendering pipeline.

Thanks, Eric, that is what I wanted to know. It must have taken some clever programming to bring requests for changes to only part of an image back into the early stages of the rendering pipeline.

  - slc
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madmanchan
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« Reply #10 on: February 18, 2009, 06:29:18 AM »
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slc, yes, there are some challenges involved there. In general, the earlier you go in the rendering pipeline, the harder it is to perform things locally under user control. This is partly because of the possible large impact on things that come later in the pipeline, as well as performance reasons. That said, in the future we will certainly have some very early-stage local processing made available to user control.
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Ben Rubinstein
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« Reply #11 on: February 18, 2009, 08:06:21 AM »
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Is that why the brighness/exposure control using local adjustments is so much noisier than doing it globally? Because it's not being done at early stage?
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madmanchan
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« Reply #12 on: February 18, 2009, 01:55:40 PM »
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I don't think so. In general the local adjustments should not be "noisier" than their global counterparts, unless you are pushing them significantly more.
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slc
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« Reply #13 on: February 18, 2009, 05:22:09 PM »
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Quote from: madmanchan
slc, yes, there are some challenges involved there. In general, the earlier you go in the rendering pipeline, the harder it is to perform things locally under user control. This is partly because of the possible large impact on things that come later in the pipeline, as well as performance reasons. That said, in the future we will certainly have some very early-stage local processing made available to user control.

Oops, now I am confused again. Are the local adjustments made early or late in the pipeline? If late, what is the technical advantage of doing them in ACR rather than in Photoshop?

  - slc
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Wayne Fox
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« Reply #14 on: February 19, 2009, 05:35:10 PM »
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Quote from: slc
Oops, now I am confused again. Are the local adjustments made early or late in the pipeline? If late, what is the technical advantage of doing them in ACR rather than in Photoshop?

  - slc
I guess I'm confused as well.  What do you mean by late?  It seems we've established it is incorporated into the RAW conversion, not applied post conversion and before tiff creation, which would be the equivalent of doing it in PS.  As long as it is in that conversion it is different than PS.

As far as technical advantage, it seems to work really well, the engineers think it is better (or as good), and I've seen no evidence it is detrimental.

There are obviously some things that are still easier in PS, and extensive brush work in LR and ACR seems to get laggy so I sometimes use PS as well. From a convenience and storage saving perspective, these adjustments are amazing, so even if the results are identical, it still a terrific feature.
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digitaldog
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« Reply #15 on: February 19, 2009, 05:43:15 PM »
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Quote from: Wayne Fox
It seems we've established it is incorporated into the RAW conversion, not applied post conversion and before tiff creation, which would be the equivalent of doing it in PS.

That's still the case, but there is an order within the Raw processing pipeline.
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Andrew Rodney
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slc
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« Reply #16 on: February 19, 2009, 06:24:19 PM »
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Quote from: Wayne Fox
I guess I'm confused as well.  What do you mean by late?  It seems we've established it is incorporated into the RAW conversion, not applied post conversion and before tiff creation, which would be the equivalent of doing it in PS.  As long as it is in that conversion it is different than PS.

....

By "late" I mean later than global adjustments. For example, if I use the Exposure setting to darken the whole image, and the adjustment brush to lighten a small part of the image, does the adjustment brush lightening happen in conjunction with, and nullify, the exposure correction, or is the whole image darkened and then sometime later the piece of the image is lightened?

  - slc
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MarkIV
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« Reply #17 on: April 27, 2009, 01:25:47 AM »
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I am sitting back reading this thread intently.  

I too have had many questions about ACR and the Raw pipeline.

I had someone recently tell me that "just because ACR 5.3 has moved some functions from Photoshop into ACR does not mean that they're necessarily being performed any differently." This person seemed to think that some of these new functions are not actually being performed on raw data and that there was little to no advantage of doing some of these functions in ACR vs PS. He also said some of the functions were not lossless.

So, I'll just sit back and try to sort this out as others put in their wiser than mine input.

Thanks everyone so far.
« Last Edit: April 27, 2009, 01:26:50 AM by MarkIV » Logged
pegelli
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« Reply #18 on: April 27, 2009, 07:05:37 AM »
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Quote from: MarkIV
I am sitting back reading this thread intently.  

I too have had many questions about ACR and the Raw pipeline.

I had someone recently tell me that "just because ACR 5.3 has moved some functions from Photoshop into ACR does not mean that they're necessarily being performed any differently." This person seemed to think that some of these new functions are not actually being performed on raw data and that there was little to no advantage of doing some of these functions in ACR vs PS. He also said some of the functions were not lossless.

So, I'll just sit back and try to sort this out as others put in their wiser than mine input.

Thanks everyone so far.

I'd say in LR/ACR they're still different because they're reversible independent of which other changes you apply before or after them. In PS that's only true if you do it on a layer and keep that layer in your saved file, and even subsequent adjustments or layers can make the process irreversible. That's another reason for me to do all that is possible in LR/ACR and only round-trip to PS when I want to do things I cannot do in LR/ACR.
« Last Edit: April 27, 2009, 07:07:17 AM by pegelli » Logged

pieter, aka pegelli
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« Reply #19 on: April 27, 2009, 09:18:58 AM »
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There are some very important differences between applying the same conceptual image processing operation in Camera Raw vs PS. One is the choice of color space. Camera Raw uses RIMM as its primary internal working space but will make temporary excursions to other spaces as appropriate, on-the-fly; in PS you generally control the working space manually and you are responsible for making intermediate conversions if needed, setting blend modes, etc. Another difference is the ordering, as noted above. In Camera Raw you can twiddle the controls in any order you want but the actual image processing routines run in a set order. In PS the operations (e.g., in layers) are applied effectively in the order of the layers.
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