This is why HDR imaging is so cool

[kirkt]

These images appear to be a simple still life shot with two off-camera flashes with umbrellas (you can see the reflections of the umbrellas in the background window). The two images essentially differ in that the flash ratio is changed.

Here's where I sound like an info-mercial. What if I told you that these images were made using ONE flash only, and they were made from the SAME HDR dataset. Yes, that's right! You too can own this power for only $19.99 plus shipping and handling if you act now!

I will write up a tutorial, but the making of these images involved shooting with one flash, starting with the flash off-camera right and shooting an exposure sequence where everything on-camera is fixed and I varied the flash output. Then I moved the flash to camera left and repeated the process. For each flash position I assembled an HDR dataset - that is, I had an HDR image for each flash position. Then I combined the two HDR images in PSCS4 using the almighty Linear Dodge (Add) blend mode and an exposure adjustment layer for each "flash". Doing al of this in 32 bit essentially permits one to adjust the flash ratio in post - infinite possibilities. With one flash and some patience, you could recreate an entire studio set up and create endless variations in your lighting and final image all in PSCS4.

The images were also tonemapped and finished all within PSCS4.

THe ability to control light like this is why HDR and 32bit is freaking cool. I am sure if I google this idea I will realize I have reinvented the wheel, but it is new to me!

Who said PS sucks for HDR?

Kirk


http://kirkt.smugmug.com/Photography/Photo-of-the-Day/PMComp-tweaked-1024/781620146_pD9mD-X3.jpg

http://kirkt.smugmug.com/Photography/Photo-of-the-Day/PMComp2-tweaked-1024/781620134_RRAhf-X3.jpg

[kirkt]

Here is one with a "third" flash added - a rimlight-esque one. The umbrella, light stand and sync cable are peeking into the frame in the upper-left corner.

Kirk

http://kirkt.smugmug.com/Photography/Photo-of-the-Day/PMCompAllThree-tweaked-1024/781635309_hzz38-X3.jpg

[navydoc]

Nice way to do multiple flash if you only have one. The colors seem to be on the red side.

I adjusted the white point only using the color chart you furnished. I only tried the one image but the head now seems blown out. There also seems to be a graininess to the images too. Is that due to the processing?

[Gary McDuffie]

I noticed the noise too, but I don't complain about that so much as mine have plenty. :) I suspect the blown out stuff is due to an overall "auto" adjustment made when you adjusted white point. Did you do that in ACR or PS? Just curious. Neat idea Kirk.

[midnight_rider]

Would it be a lot easier to just use layers and combine images?
I do not see where HDR helped here.

[kirkt]

The third image added noise due to my hasty processing of the "rimlight" hdr. Need to do it again. Navydoc - you now see why HDR is better - no blown highlights when try to make adjustments to the 32 bit data. Your attempt at making the adjustment demonstrates why 32 bit data rocks. Also, the white patch on the ColorChecker chart is not receiving the brightest lighting, so it is not surprising that when you chose it to set your white point it blew out the brighter parts of the image. I had gelled the flash with CTO orange to match the room's tungsten overhead light (i was going to shoot a 4th set with just the room light and add that in as well but never got around to it). When I balanced the image I added a little bit of orange/red back in.

Midnight_rider - try this experiment in 8 or 16 bit using layers - you can't do this unless all of the images you are trying to combine have more or less the same luminance range. Even then you can't adjust the flash ratio very much to get distinctly different looks. You need HDR data for each flash to turn each one up or down significantly and you need to combine (add) the lighting from each in 32 bit otherwise, you will blow everything out. Try it yourself with a single flash image for each position (i.e., just two total LDR images to start with)- shoot a RAW for each flash position (set the flash to the same power and about the same distance form the subject so the flash exposure is similar). Adjust each RAW and then try combining the two images in 16 or 8 bit. You will quickly realize the limitation. Once you play with this in full HDR you will start to understand the significance of 32 bit processing a little bit better.

Kirk

[navydoc]

Kirk...please don't misunderstand. I love hdr and the range it gives me for adjustments. I did the quick one click 'set white point' using the levels adjustment in CS4 without realizing you had used a gel.

[kirkt]

Navydoc, no worries. Once I write up the procedure it will be a little bit easier to understand these images.

Kirk

[kirkt]

Following up on a bunch of things, I revisited some of the HDR data generated in this exercise and, like a lot of things, rediscovered the most excellent HDR tone rendering of Picturenaut (http://www.hdrlabs.com/picturenaut/index.html). Look at the crappy, hastily tone rendered images from the above posts and it is clear the the Picturenaut bilateral tone map is superior in all aspects - and truly blazing running in XP on my Mac Book Pro under VMWare Fusion. Damn, I wish I could remember all of these incredible tools all the time.

Here is the Picturenaut version:

http://kirkt.smugmug.com/Photography/Photo-of-the-Day/PicturenautOut/855881101_nf4Co-X3.jpg

Clean and true to the colors present in the scene. Preview looks like the output, processed file. Free too. Please consider a donation to keep this great tool advancing. The original tone maps are embarrassing in comparison. Always learning....

Awesome.

Kirk

[wolfden]

try PS5 now?