I thought I’d spend the 2nd day of 2015 talking about “True HDR” versus “HDR effects”.
One is actually HDR, the other isn’t.
A bit of background. HDR is unique to digital photography, because back in the olden days (Pre-Bush Jr) most photography was done via a chemical process. Exposing film in a camera caused a reaction with light sensitive silver nitrate compounds, which were then dunked in various chemical baths to be “developed”. It was during this time/temperature process that the real magic of photography occurred. You never got to see the results until after this process, and I can vividly recall my palpitating heart the first time I opened a processing tank to view my first ever developed roll of Tri-X. Almost beat out by my first ever solo landing in a Cessna… Almost.
Film had a small range of contrast it could handle before it either made shadows go completely black or the highlights went complete white. This range depended on the film you were using. Slide film has the lowest (narrowest) contrast range; certain negative films the widest range.
With black and white negative film one could adjust exposure and then development to compress the image, also called “Zone System”. The Zone System is best remembered as “expose for shadows, process for highlights”
This was best used by photographers utilizing large format cameras, where a single frame could be processed differently from the other frames.
With digital, there is really no processing. So HDR was developed as a way to compensate for the limited exposure range of digital sensors. This is accomplished by making several exposures of a scene, bracketing each exposure to get images with good shadow detail then images with good highlight detail.
Using Photoshop or another piece of software, you then could stack the images and merge them into one single image with shadow and highlight detail. There are various effects that happen, and a good HDR image is almost like what the human eye can see.
Everything else is artistic intent.
HDR effects are simply taking a single, evenly exposed image and getting the HDR look by compressing highlights and shadows and causing edge effects. It’s not really, truly HDR. It’s just an effect.
That effect certainly can’t bring out details in shadows in a scene with extreme range.
Let’s take an extreme example. I uploaded to my gallery a scene of a piece of gnarled tree trunk with the sun backlighting the wood and pine needles. This one I did a 7-EV bracket to allow of the extreme brightness of the direct sun peeking through the pine needles.
Here’s a collage of the 7 exposure range I used….
Looking at the contact sheet, you can see where my trusty Nikon thought the proper exposure should be, exposure #4. Wow… It’s losing the shadows badly… and the better single exposure is #5, or plus 1 EV.
And that’s where True HDR comes in.
Using only photoshop, I did a Merge to HDR pro, and played with the settings to achieve a very nice HDR of the scene.
Next post I’ll examine several of the Android apps for HDR photography….