White Balance correction in spherical HDR pano's

[Mike Dols]

Hi there everybody!

I do a lot of spherical panorama's. I started outdoors, wich is easy regarding to the WB: one setting is good for the whole spherical image. Now i'm doing an indoor virtual tour at an nearby monastery / abbey.

This offers some challenging WB issues, due to windows showing blue daylight, and the yellow tungsten lighting.

I've tried retouching them in PS after tone-mapping when it became most visible, but the 8-bit image tends to generate some banding artifacts. The HDR Is resticted in editing capabilities, but the Channel Mixer Adjustment Layer seems to do an ok job, but tedious to find the right color settings. So the best shot to me seems the original RAW files before HDR merging, but i cannot seem to find any local WB adjustment possibilities in Photoshops CameraRaw...

I will certainly try and find some more ways, but maybe i'm thinking too difficult. I was wondering what you guys do in these cases?

I've attached a tone-mapped image with big WB differences, so you can see what i mean. Please note this is not a "beauty" tone-map, but it shows the WB difference pretty well.

Many thanks in advance!

Peace out!

[Erik Krause]

Am 12.10.2012 18:46, schrieb Mike Dols:

> I've tried retouching them in PS after tone-mapping when it became most
> visible, but the 8-bit image tends to generate some banding artifacts.

Output with 16 bit. No need to reduce quality before the very last step.

> The HDR Is resticted in editing capabilities, but the Channel Mixer
> Adjustment Layer seems to do an ok job, but tedious to find the right
> color settings. So the best shot to me seems the original RAW files
> before HDR merging, but i cannot seem to find any local WB adjustment
> possibilities in Photoshops CameraRaw...

There is a split toning in more recent ACR versions. However, I doubt it
is of much use, since windows and interior is of same brightness.

One way to reduce the issue in PS is a saturation adjustment layer:
Select Blues, eventually eye-drop the correct hue and pull saturation
down until it doesn't look wrong anymore. If this procedure also reduces
indoor blue (from paintings f.e.) paint the adjustment layer mask black
with a soft brush in those regions.

If you have larger and painted windows you can stitch the panorama twice
from two versions of the images - one for indoor lighting, one for
outdoor lighting - using the project file of the first image set as a
template for the second one. Don't optimize the second one! Overlay them
both in PS and paint masks accordingly.

As for your example: Use a better HDR program wich gives you more
realistic colors and/or don't oversaturate. Exposure fusion is often
better than tonemapping. My current favorite is SNS-HDR lite, which is
free and gives superb results out of the box (use before stitching since
it doesn't take care of the zenith)

BTW.: There are lots of tutorial on the web how to deal with mixed lighting.

--
Erik Krause
http://www.erik-krause.de

[Mike Dols]

Danke Schön Erik!

Some useful tips there, thanks a lot!

The 16-bit file is a good tip, why haven't i thought of this myself...

- But why stitch the pano twice (you can't optimize a "templated" project without control points indeed), you could just tone-map the 32-bit image twice, saving the stitching time.

- The saturation adjustment layer does not a very good job, when there is ONLY blue color in the window, its just turns to grey-shades. I'll try to overlap it with some Photo Filter or color overlay.

- What do you mean by a better HDR program? to merge to HDR or to tone-map? This is my workflow now: Adjust RAW files with color card generated color profile and save as DNG in ACR. Photomatix to batch-merge the images to single HDR frames. PTgui to align the single RAW files to create a template which is applied to the HDR images for stitching, save the panorama and single layers as HDR. Retouching like nadir masking and ghosting in Photoshop, and then tone-map with Photomatix or PS (Photomatix for the creative results, Photoshop for the realistic tone-mapping, mostly only curve adjustments, no color adjustments.

I've tried searching google and youtube with keywords like "local WB adjustment" but it did not get me to the right subjects. Hence i thought i'd ask it here.

I'll post the results when I've tried,

Thanks again!

Op vrijdag 12 oktober 2012 18:46:30 UTC+2 schreef Mike Dols het volgende:

[Ken Warner]

Lightroom has a spot tool that lets you de-saturate a small area and let's you paint that area with an adjacent color. I use it for sun spots and it does a pretty good job.

On 10/12/2012 2:47 PM, Mike Dols wrote:
> Danke Sch�n Erik!

[Erik Krause]

Am 12.10.2012 23:47, schrieb Mike Dols:
> - But why stitch the pano twice (you can't optimize a "templated"
> project without control points indeed), you could just tone-map the
> 32-bit image twice, saving the stitching time.

Once from the whitebalance for interior lighting, once for exterior:
white balance bracketing...

> - What do you mean by a better HDR program? to merge to HDR or to
> tone-map?

To tonemap. Photomatix boosts colors too much, even with Fusion method.
PTGui internal exposure fusion, enfuse or SNS-HDR are way better.

> This is my workflow now: Adjust RAW files with color card
> generated color profile and save as DNG in ACR. Photomatix to
> batch-merge the images to single HDR frames. PTgui to align the single
> RAW files to create a template which is applied to the HDR images for
> stitching, save the panorama and single layers as HDR. Retouching like
> nadir masking and ghosting in Photoshop, and then tone-map with
> Photomatix or PS (Photomatix for the creative results, Photoshop for the
> realistic tone-mapping, mostly only curve adjustments, no color
> adjustments.

Way too complicated in my opinion. Save to 16 bit TIFF in ACR. Exposure
fuse f.e. using enfuseGUI, stitch, post process in PS. Alternatively
load all brackets into PTGui pro and stitch directly, but I don't like
this anymore, since the first variant gives way better control, is much
faster and easier to post process.

BTW.: If you save to DNG in ACR no corrections are applied, neither
chromatic aberration nor white balance nor anything else. You can as
well use the raw directly. However, using raw in PTGui isn't recommended
for top quality.

> I've tried searching google and youtube with keywords like "local WB
> adjustment" but it did not get me to the right subjects.

Search for "mixed lighting"...

[Mike Dols]

"Once from the whitebalance for interior lighting, once for exterior: white balance bracketing..."

I get your idea, it makes good sense. but why stitch twice? why not just tone-map twice? more WB control on the single images is your thought?

"To tonemap. Photomatix boosts colors too much, even with Fusion method. PTGui internal exposure fusion, enfuse or SNS-HDR are way better."

Photomatix is only used for creative, booming results, i find it gives some kind of a blurry "soft focus" effect too. I aways use PS to tone-map realistic images. Photomatix however is super for its batch merging abilities. I will definetely check out this SNS-HDR, never heard of it before.

"Save to 16 bit TIFF in ACR. Exposure fuse f.e. using enfuseGUI, stitch, post process in PS. Alternatively load all brackets into PTGui pro and stitch directly, but I don't like this anymore, since the first variant gives way better control, is much faster and easier to post process."

Absolutely true. But when i use the HDR files to align and set up the .PTS file, it just gets laggy and slow. hence the template made from the single files. Except from this and the TIFF, i do it like you descibe it in the first manner.

"BTW.: If you save to DNG in ACR no corrections are applied, neither chromatic aberration nor white balance nor anything else. You can as well use the raw directly. However, using raw in PTGui isn't recommended for top quality."

Your'e right! I tested it and its true... i didn't know this. How embarrassing! But the corrections (like an extreme WB setting) is obviously visible in the DNG file in windows explorers thumbnails, even with the sidecar files deleted! Maybe this set me off on the wrong foot... so it's 16-bit TIFF only from now on, my HDD will love it :(

Thanks alot Erik!

DemonDuck, i will check lightroom and see how this works, thanks for the tip!

Heres the result from the WB correction with the saturation adjustment layer, looking good!

[Erik Krause]

Am 13.10.2012 01:33, schrieb Mike Dols:
> "Once from the whitebalance for interior lighting, once for exterior:
> white balance bracketing..."
> I get your idea, it makes good sense. but why stitch twice? why not just
> tone-map twice? more WB control on the single images is your thought?

Well, I always do white balance setting at the raw level, since I don't
use HDR tonemapping - I don't like the results. If you are happy doing
it at the tone mapping level it should be ok.

> "Save to 16 bit TIFF in ACR. Exposure fuse f.e. using enfuseGUI, stitch,
> post process in PS. Alternatively load all brackets into PTGui pro and
> stitch directly, but I don't like this anymore, since the first variant
> gives way better control, is much faster and easier to post process."
> Absolutely true. But when i use the HDR files to align and set up the
> .PTS file, it just gets laggy and slow. hence the template made from the
> single files. Except from this and the TIFF, i do it like you descibe it
> in the first manner.

You should know that if you feed raw files directly to PTGui they have a
slightly different pixel size. It could be that photomatix uses dcraw as
raw converter as well and hence delivers the same size. However, I
wouldn't rely on that since f.e. ACR gives the same size like in-camera
jpeg.

> "BTW.: If you save to DNG in ACR no corrections are applied, neither
> chromatic aberration nor white balance nor anything else. You can as
> well use the raw directly. However, using raw in PTGui isn't recommended
> for top quality."
> Your'e right! I tested it and its true... i didn't know this. How
> embarrassing! But the corrections (like an extreme WB setting) is
> obviously visible in the DNG file in windows explorers thumbnails, even
> with the sidecar files deleted! Maybe this set me off on the wrong
> foot... so it's 16-bit TIFF only from now on, my HDD will love it :(

The thumbnails use an internal jpeg representation of the corrected DNG.

I personally wouldn't use anything else than ACR for raw conversion.
Highlight restoration is superb, CA correction is the best I ever seen
and works fully automatic meanwhile and colored fringes are remove
perfectly. Tonality and sharpness are very good, too, even if denoising
is applied. I used DPP for a long time and ever thought my cheap Zenitar
lens couldn't deliver enough sharpness (and was jealous of all the EF
8-15mm users) but not anymore...

[Mike Dols]

"Well, I always do white balance setting at the raw level"

That's what I wanted to know, one does have more WB control in ACR than with tonemapping. Check.

"You should know that if you feed raw files directly to PTGui they have a slightly different pixel size"

I feel another moment of shame coming up... tested it and again your'e right! Again i didn't knew...

"The thumbnails use an internal jpeg representation of the corrected DNG."

That explains...

"I personally wouldn't use anything else than ACR for raw conversion."

I don't :-). Also for "normal" images like a wedding shoot. an outblown wedding gown can be easily restored to a detailed, correctly exposed dress. Especially when shooting 14bit. I just love ACR.

Well, You ceratinly gave me alot of new tips and some fundamental knowledge i should have known. I'm really gonna have to change my workflow now.

Also vielen Dank fuer deine gute Tipps! Ich werde sie zur Herzen nehmen!

[Mike Dols]

I've had some time now to play with your advice, and i must say it works great! It takes some more processing time, but the double stitch and TIFF workflow really gives me the advantage on the WB control and overall image quality!

Handled some pretty complicated WB scenes with three main white balance targets, stitched three versions and layered in tiff. worked great.

Thanks again, lesson learned!