[HDR-photo] HDRI Book and Jpeg brackets

[listmail at mab3d.com]

On Nov 24, 2007, at 2:01 PM, Sam Kittner wrote:

> Does anyone see reasons not to shoot hdr intended images as jpegs?   
> I will do some tests for myself, but wondering if there is any  
> difference others have found?

Hi Sam,
I can imagine quite a few reasons to shoot *multiple bracketed RAWs,*  
which become more apparent the higher the number of brackets or EV  
you capture:

- Some of your camera's processing/ JPEG creation cannot be  
completely controlled. (ie: saturation, sharpening, tonal curves,  
compression amount, and other things done "to make a nice image")

- Your lens has lots of aberrations/ vignetting to correct for.  
(removing these in RAW processing is less destructive than on a JPEG,  
and almost no tools will fix these in 32-bit once the HDR is made)

- White balance isn't "spot on" when you started shooting. (I suck at  
WB calibration until I'm at home in ACR, but that's me.)

- In highly dynamic scenes you are shooting more than 3 brackets  
+-2EV on a conventional sensor (not Foveon, not Fuji) camera. (beyond  
4 EV "good looking" individual source images *do not always equal*  
great looking output, either 32-bit or tonemapped - see the in-camera  
processing comment above.)

- You are shooting for any kind of technical use of the HDR image  
(fe: "light probes" for 3D rendering, forensic photography,  
astrophotography)

There are probably more reasons, but the bottom line is really how  
many brackets you are capturing and how good/ bad your camera's JPEGs  
are. Beyond that, frankly, if storage or capture/ write speed of RAWs  
is an issue for anything under 15 brackets, you probably need a new  
camera. My ancient 300D can suck up 7-10 brackets in RAW as fast as  
the shutter will trip in bright daylight, so I base the "15" number  
on a 5 year old camera.

Okay, there *is* one glaring reason to shoot multiple JPEGs instead  
of RAWs (and I think this applies to more photographers than would  
admit): you don't fully understand *how* to process RAW files outside  
of the presets in the software that came with your camera or using  
the "Auto" buttons in ACR.

Truly, it took me about 6 months and thousands of images (and the  
help of lots of people) to figure out just what RAW processor  
settings to use for my "technical" HDRs, but I think it is pretty  
obvious that lots of contrast & saturation boosting, highlight  
recovery, shadow darkening and tonal curves are *not* going to help  
the individual brackets of an HDR (most especially if it is done with  
"auto" anything and each bracket is differently processed). Plus if  
you are only going to tonemap the HDR after making it, why repeat the  
work of "prettying up" each bracket when you can do it for all of  
them at once as an HDR in Photomatix or DPHDR or Picturenaut or  
whatever tonemapper?

-Mark