June 19, 2018, 07:04:09 AM

Author Topic: HDR: Do you process RAW images first before combining?  (Read 6381 times)

cayenne

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HDR: Do you process RAW images first before combining?
« on: March 12, 2018, 01:00:19 PM »
Just curious....

I was thinking, that once you combine your multiple exposure images, that is the last time you will have opportunity to do any RAW manipulations to them.

Do ya'll do any RAW changes before combining the images into an HDR for tone mapping?

If so...what?

Since you are combining images...are there any RAW changes you have to be careful of in order to not have problems multiply as they combine?

Thanks in advance!!

cayenne

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HDR: Do you process RAW images first before combining?
« on: March 12, 2018, 01:00:19 PM »

Don Haines

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Re: HDR: Do you process RAW images first before combining?
« Reply #1 on: March 12, 2018, 01:09:22 PM »
Just curious....

I was thinking, that once you combine your multiple exposure images, that is the last time you will have opportunity to do any RAW manipulations to them.

Do ya'll do any RAW changes before combining the images into an HDR for tone mapping?

If so...what?

Since you are combining images...are there any RAW changes you have to be careful of in order to not have problems multiply as they combine?

Thanks in advance!!

cayenne

I have used lightroom, and just feed in the RAW files as is.....

They combine to make an additional file, and that is the one that gets edited.


hmmmmm......

I think that when I get home tonight I am going to try an experiment..... 1st try, combine the images as untouched RAWs, and 2nd try, process the individual RAW files and then combine them.... I have no idea if it will make any difference.......
« Last Edit: March 12, 2018, 01:42:43 PM by Don Haines »
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GammyKnee

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Re: HDR: Do you process RAW images first before combining?
« Reply #2 on: March 12, 2018, 01:37:09 PM »
I do lens-related fixes (distortion, CA etc) prior to blending, but everything else comes after that.
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Frodo

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Re: HDR: Do you process RAW images first before combining?
« Reply #3 on: March 12, 2018, 02:51:06 PM »
If you are combining multiple HDR images into a panorama, I think you would have to merge into pano first, then merge into HDR. HDR will change the exposure of different parts of the pano and you will see the joins.
The LR HDR process generates a dng file which will have much, but presumably not all, of the maleabity of the RAW file. I do basic processing such as lens corrections before merging into HDR. Only once I see how the HDR dng turns out can I really visualise how the final image will evolve.
I was excited about HDR when first introduced into LR, but now it use it only a little. I am usually able push shadows and pull highlights sufficiently on my 5Ds and 6D files in most cases. The main issue is ghosting from moving leaves, water, etc.
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Zeidora

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Re: HDR: Do you process RAW images first before combining?
« Reply #4 on: March 12, 2018, 07:18:25 PM »
Luminar also reads RAW files.
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Don Haines

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Re: HDR: Do you process RAW images first before combining?
« Reply #5 on: March 12, 2018, 07:32:01 PM »
If you are combining multiple HDR images into a panorama, I think you would have to merge into pano first, then merge into HDR. HDR will change the exposure of different parts of the pano and you will see the joins.
The LR HDR process generates a dng file which will have much, but presumably not all, of the maleabity of the RAW file. I do basic processing such as lens corrections before merging into HDR. Only once I see how the HDR dng turns out can I really visualise how the final image will evolve.
I was excited about HDR when first introduced into LR, but now it use it only a little. I am usually able push shadows and pull highlights sufficiently on my 5Ds and 6D files in most cases. The main issue is ghosting from moving leaves, water, etc.

For panoramas, AutoPano Gaga allows you to import everything raw as one step, and then start it stitching like you would for any normal panorama
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cayenne

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Re: HDR: Do you process RAW images first before combining?
« Reply #6 on: March 13, 2018, 10:45:22 AM »
Interesting slant on doing the HDR Pano thing....

But in general I was thinking that once you combine into HDR, you lose the true, low level ability to push and pull the RAW data that is non-destructive....

I thought about lens corrections myself and do that....but what about things like saturation?  Vibrance?

Once you are in HDR combined, you're basically limited on how much you can push/pull these things as much as you can with a jpg.....

C

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Re: HDR: Do you process RAW images first before combining?
« Reply #6 on: March 13, 2018, 10:45:22 AM »

Frodo

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Re: HDR: Do you process RAW images first before combining?
« Reply #7 on: March 13, 2018, 02:42:33 PM »
Once you are in HDR combined, you're basically limited on how much you can push/pull these things as much as you can with a jpg.....

C

I understand that dng is similar to RAW and much more maleable than jpg. Hasselblad, Pentax and Leica use it as their "RAW" format.
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Ladislav

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Re: HDR: Do you process RAW images first before combining?
« Reply #8 on: March 13, 2018, 05:51:40 PM »
Hmmm, interesting question. My assumption was that it does not matter when merging to HDR in Lightroom since I expected that it takes RAW data and merge that to HDR DNG which is still raw so all modifications should still happen on top of that.

Different story is exporting for merge to Photomatix. In such case I do very basic RAW processing first - camera profile, lens profile and chromatic aberration, color temperature.
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stevelee

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Re: HDR: Do you process RAW images first before combining?
« Reply #9 on: March 13, 2018, 07:52:44 PM »
In Photoshop you can open files as Smart Objects, and that will retain editability. (Or "edibility," as auto-correct prefers.)

ken

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Re: HDR: Do you process RAW images first before combining?
« Reply #10 on: March 13, 2018, 08:05:48 PM »
I do a lot of HDR work. I typically go from Lightroom to Photomatix Pro then back to Lightroom. I always apply lens profile to the individual files, and then I knock down highlights as needed. Highlights are the big thing that I pre-process. Whether it's the sky during the day, point lights at night, or daylight from a window. Sometimes I'll toy with clarity and contrast, but typically I'll do that on the merged file when I get back it in Lightroom.

Once I get the merged file back in Lightroom, I usually "Group into Stack" the originals so that I can find the groups easier in the future. (You have to unstack to export to Photomatix Pro again.)  That's just an organizational tip.

Just experiment and see what works! It's easy enough to go round-trip several times with a set.
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Don Haines

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Re: HDR: Do you process RAW images first before combining?
« Reply #11 on: March 13, 2018, 10:36:07 PM »
Did a quick experiment.....

Processed the RAW files and then ran them through the Lightroom HDR, and ran the unprocessed files through Lightroom HDR..... got essentially the same result....

First photo, pre-processed....
Second photo, no pre-processing....

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LDS

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Re: HDR: Do you process RAW images first before combining?
« Reply #12 on: March 14, 2018, 06:55:10 AM »
I was thinking, that once you combine your multiple exposure images, that is the last time you will have opportunity to do any RAW manipulations to them.

When you load an image, it won't be in "RAW" anymore - it will demosaiced, camera profile applied, etc. etc.

"RAW" means you have the data as read from the sensor, but most image processing applications need to transform them into a common format they can manipulate.

In memory, the image will be some sort of 16-bit RGB image, hopefully in some large enough color space. When you open it in Lightroom, IIRC the in-memory format is very similar to that used internally by DNG, in its variation of ProPhoto RGB color space.

Any image stored with enough bit-depth and large enough color space can be edited with ample space before too many data are lost, clipped, etc. Manipulating a RAW file or a 16 bit ProPhoto RGB TIFF file is quite the same, especially since they will transformed into the same in-memory format.

Thereby, if after the merge the image is still in a "large" enough format, it can be edited as if it was a RAW - how much depends on the merging algorithm and the resulting image.

The advantage of RAW is just you have the original camera data, so any improvement to the "load" algorithms (demosacing, camera profiles, etc.) can be re-applied to the sensor original data, something you can't do if those are no longer available.

Returning to your question, processing RAW images before merging may change the merge result - the algorithms will work on different data - I'd be very careful also about those who alter some pixels only (i.e. sharpening, which changes pixels along the edges) because they could be applied in different ways in the different images, and may result in artifacts later. Other may have no impact.

IMHO, unless you have a good reason to do otherwise, processing should be applied to the merged image. If you think pre-processing some images will yield better results, do it - but not because you think you lost the opportunity of "RAW processing" later.

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Re: HDR: Do you process RAW images first before combining?
« Reply #12 on: March 14, 2018, 06:55:10 AM »

jaell

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Re: HDR: Do you process RAW images first before combining?
« Reply #13 on: March 21, 2018, 08:53:51 PM »
Photomatix recommends processing RAW to TIFF before loading images (as a first step, before aligning, deghosting, etc.). That recommendation is based on the pre-processing to remove any/all artifacts from your individual images--because those artifacts will compound as you're pushing saturation, contrast, etc., in the HDR process.

So if you have lens distortion, chromatic aberration, fringing, flare, vignetting, etc., you want to address that before you move to HDR processing. Ditto with any white balance correction you need to do. As I primarily use HDR on outdoor shots, and often desaturate (even to full BW), I don't need to do a lot of white balance correction.

For me, when I need the intermediate step of RAW->TIFF prior to HDR is, as others have pointed out, when I'm stitching panoramas. You must-must-must stitch first--you can't just HDR your individual slices and then stitch the HDR-ed images together. And, if it isn't obvious, you need to crop your stitched panos before the HDR process, because if you try to process an image with the funky borders from the stitching process, it'll throw off all the contrast and DR adjustment.

I've been using Photomatix for almost 9 years now, with 'normal' images and IR, and I've tested individual projects letting Photomatix use the original RAW files and using TIFFs processed (by both ACR and DPP) from the RAW files with no adjustments. I can't tell any difference, so I believe Photomatix's RAW processing is just fine for my uses. I do tend to pre-process in DPP when I'm using IR images that I want to end up BW, because the little bit of color that the RAW files have can produce some odd/jarring results in Photomatix. On occasion I've tweaked the TIFFs in Photoshop (using Nik Silver Efex, applying red filter) before porting over to Photomatix, but that's a lot of work--the main benefit being smoother skies without weird artifacts.

I'd say the biggest thing, if you're doing HDR landscapes with a wide angle, is to address vignetting. If you're going for a very "HDR" look, any vignetting in your RAW images can become very pronounced.
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scottkinfw

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Re: HDR: Do you process RAW images first before combining?
« Reply #14 on: March 21, 2018, 10:58:03 PM »
Just curious....

I was thinking, that once you combine your multiple exposure images, that is the last time you will have opportunity to do any RAW manipulations to them.

Do ya'll do any RAW changes before combining the images into an HDR for tone mapping?

If so...what?

Since you are combining images...are there any RAW changes you have to be careful of in order to not have problems multiply as they combine?

Thanks in advance!!

cayenne

Excellent question.  I have wondered this myself.  Thanks for asking.


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Re: HDR: Do you process RAW images first before combining?
« Reply #14 on: March 21, 2018, 10:58:03 PM »