November 01, 2006

Creating professional HDR images

Ryan McGinnis of Backing Winds has posted a solid intro to creating high dynamic range images in Photoshop.  "Photoshop CS2 has a little-known (it seems) built-in HDR assembler," he writes, "that, while lacking the ‘make my photo look like an acid-trip‘ tone-mapping features of Photomatix, is capable of creating extremely realistic or extremely surreal HDR images." He ends up with a beautifully exposed image of the interior of a cathedral, although it would be nice to get a bit more info on how he (very capably) tone-mapped the 32-bit file down to 16bpc. [Via]

I mentioned the article to Photoshop engineer John Peterson, who worked on the Merge to HDR feature.  He points out a few things:

  • Instead of opening images via Camera Raw, setting their parameters, and then choosing Merge to HDR, you can simply select them in Bridge and choose Tools->Photoshop->Merge to HDR (or from within Photoshop, choose File->Automate->Merge to HDR).
  • Merge to HDR and Camera RAW have a secret handshake where M2HDR tells Camera Raw to always zero out the exposure-related parameters (Exposure, Shadows, Brightness, Contrast) and guarantee linear output.
  • "The alignment feature doesn’t usually work so great" – Fair enough, and we have some good ideas on how to improve it.
  • "You don’t need to adjust the histogram…it has no effect on the final image" — This is true, although it does set the exposure value for the finished document.

Speaking of HDR, here’s an otherworldly photo of an Italian cathedral.  And John P. speaks highly of the Merge to HDR chapter in Mikkel Aaland’s Photoshop CS2 Raw.

Posted by John Nack at 9:40 AM on November 01, 2006

Comments

  • Darren Addy — 8:02 PM on November 01, 2006

    I had no idea that I would create the HDR monster that is Ryan McGinnis when I started an innocuous little thread in a Stormtrack forum called “High Dynamic Range Imaging”. He latched onto the concept with a vengence. Ryan is my stormchasing mentor and he uses Photoshop in his job color correcting at the Lincoln Journal-Star newspaper (in Nebraska’s capitol city). If you need capable beta testers, you should put him on your list. I imagine he has sold a few copies of Photoshop for Adobe with his “how to” article which has been picked up all over the place, including Digg and del.icio.us/popular.
    [Cool–thanks for the back story! We’re always psyched when people find a feature that we think is really cool, but which has remained a bit obscure, and then tell others about it. –J.]

  • Brajeshwar — 10:03 PM on November 01, 2006

    I once did a Primer on HDR while I was trying to learn the details, collecting related articles to the same.

  • Joe Lencioni — 8:39 PM on November 02, 2006

    HDR is one of my favorite things about Photoshop CS2. I’d love to see what you guys have in store for it.

  • Katrin Eismann — 4:46 AM on November 06, 2006

    Hi John,
    Within the secret handshake between ACR and PS HDR processing is the Curve also set to Linear? In my experience zeroing out all ACR controls created better HDRs then letting ACR run on automatic.
    Thanks,
    Katrin

  • Ryan McGinnis — 3:17 PM on November 25, 2006

    Hi, John! Thanks for linking to me — it’s cool to see the staff of Adobe out and about listening to their customers. Seeing as the CS2 HDR implementation is Adobe’s first go at this genre of photography and is already quite cool, I have high hopes for where the HDR feature is going.
    As for the 32->16bit tonemapping, I began with the curve transformation shown in the tutorial, “and then a miracle happened”. ;) Geeze, you want me to give away the secret sauce recipe? Okay, okay, you talked me into it. Basically, I first applied the shadows/highlights tool, with the shadows mode shut completely off and the highlights set to 4% (just enough to soften up the harsher highlights… very subtle, but it helps.) I then switched over into Lab mode and did a slight compression/clip of the A/B channel in curves, bumping saturation. After that, I worked with curves adjustment layers to selectively open up some of the shadows and midtones, and also to put slight s-curves into certain areas for enhanced contrast in certain areas of the shot. After a quick switch back to RGB, I finished up by sharpening with Fred Miranda’s excellent plugin script “Intellisharpen II”, which you should licence immediately from the guy and include in the next release, because dang, it’s a great tool! ;)
    Thanks again, and thanks for Photoshop. I’ve been using it since back when the dang thing came on a set of 3.5″ floppies, and it just gets better and better.
    [Great stuff, Ryan. Thanks for the tutorial, and for the feedback. –J.]

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