HDR: Merge Raw images or jpg?

May 2nd, 2014
I'm at square one & have JUST begun to sample HDR. With two cameras, my CoolPix shoots 2 images...it's not too bad. With my NIkon D5000 I can shoot 3 and I shoot RAW images. So when I merge my 3 images, should I use the unaltered Raw ones? And when I select the finished image I want, should I alter it further with curves, exposure, etc? One other question...How do I know what span to bracket from "AE0.7 to AE2.0"? I don't understand what that achieves. In advance, thank you for spending a minute here with your suggestions. I've loved all I've seen in HDR since I joined in 2010, but it's taken me this long to get my feet wet.
May 2nd, 2014
Hi, HDR stands for "High Dynamic Range" and when human brain can usually adapt to the scene with high dynamic range the cameras unfortunately dont meaning if for example you want to properly expose bright areas the darker ones will very likely be underexposed or too dark. This is where HDR technique comes in handy so by bracketing exposures you expose all areas and then merge them with HDR software into the final image. Usually 3 JPEG files wit EV-1; EV 0; EV+1 are enough but depending on circumstances you can go as much as 5 or even more. Choosing the increments of bracketing solely depends on what it takes to have all parts of image properly exposed. The other method is using a single RAW file this is so called pseudo HDR and for me in most cases works even better than combining JPEG files as this allows to eliminate ghosting issues and HDR software usualy does all the job for you since raw file contains much more data than JPEG in most cases you can easily have 3 bracketed photos from single RAW file. There are plenty of free HDR software but i cant comment about them cause I use Photomatix Pro which is extremely good software but it's not free.
May 2nd, 2014
I use Photomatix Pro for my HDR tone mapping. Typically, I will take between 7 and 10 photos, each 1-stop apart, centered around the ideal exposure. Using Photomatix Pro, I combine the RAW images and then tone map accordingly. I save that as a 16-BIT TIFF and bring the TIFF into Photoshop Elements 10. That, unfortunately, means converting to 8-BIT since 16-BIT layers aren't supported. The remember of my processing, though, takes place in PSE.
May 2nd, 2014
@kannafoot taking 7 or 10 pic around "ideal" exposure doesn't really make sense since the whole idea of HDR technique is to use it when u actually CAN'T get the ideal exposure throughout the whole image the principle is to properly expose different areas of the whole image and then merge them into a final image. Unless you want some artistic effects of course lol :)
May 2nd, 2014
I use one RAW image and save as a JPG then EV+2 the RAW and save as another JPG and then EV-2 the RAW and save as yet another JPG. I will then use the three JPG's in Luminance HDR to create a final JPG HDR image.
May 2nd, 2014
@tauras Tauras, by using the ideal exposure as the mid-point, you're stretching it 5 stops in either direction which is well beyond the normal dynamic range of a camera. The assumption, naturally, is you're starting with an image that would have the whites and blacks clipped at the ideal exposure point, meaning you have a scene that has more contrast naturally than the camera can handle.
May 2nd, 2014
@kannafoot fair enough Ron I got your point :)
May 2nd, 2014
@tauras @kannafoot @richardcreese You're all obvious quite adept at using this, but I do get the drift. It will be interesting to try the variables with one image, Richard, but I'd like to figure 3-image HDR out first. I have Photoshop and open my 3 images in Bridge which gives me choices for how I'd like the finished picture to look. (Until recently I didn't realize there WERE choices) So as I understand this, I open my 3 RAW images... (and I better understand the + and - bracketing now, depending on light conditions) select my choice and THEN convert it to 8 bit before opening and finalizing it? (Dare I ask if more than 3 bracketed images are available on most cameras? OK...tell me but I'm focusing on the 3 I seem to have available until I get a handle on this baby step!) I may be back with another question at a later time, so thanks, Taurus, Ron & Richard! "365 Stars" for each of you!
May 3rd, 2014
Lots of good information here. Thank you everyone for the tips.
May 3rd, 2014
Thanks so much for the information. I went to a photo exhibit opening tonight and had a chance to question the photographer. He mentioned some of these techniques. You've really helped me understand the HDR process more clearly!
May 3rd, 2014
@mittens @paulam I'm glad you two were also interested in this information; I hoped it might also help others. I've been altering some 3-shot photos tonight, and it's very interesting that the same technique doesn't work best for everything... Paula, if you have anything additional to add to this, I'm interested in knowing more! How nice to have the opportunity to speak directly with the photographer!
May 3rd, 2014
@Weezilou Can you explain a little more about + or - depending on light conditions? I have only used + and didn't even think about lighting -- duh -- so am very interested in learning about this!
May 3rd, 2014
If you have Photomatix or Merge to HDR in Photoshop, do consider doing it to the raw files and work with at least 16 bit merges. Personally, I process HDR brackets in 32 bit mode and do the tone adjustments in Adobe Camera Raw after merge to HDR in Photoshop. I don't much admire the "HDR look" and ACR works beautifully for me. Working on 8 bit jpegs can only leave "holes" in the tone palette as you push and pull HDR output, it's almost a given that you'll "posterize" at least some of the edges.
May 3rd, 2014
@taffy @frankhymus Wow,,,I'm replying to the two of you because I think if you both as the Master Class teachers on this site! (Frank, first, I comprehend a great deal of what you've said, having been toying with the bracketed shots I took to "play" with, but will return in a moment. I'll tell Taffy "what I think I mean", and feel free to step in & make corrections as I'm only saying what I think it is I should do... In the extreme, if you're on the beach on a bright day, and people are in the shade under an umbrella, (am I correct here, Frank?) I think that is the time one might want to bracket the full +2 and -2 around what might seem to be the best exposure...probably on the subjects under the umbrella if that's your central point of interest (?) What I'm unclear about is how best to use the smallest bracketing (0.3 and up...) ...

Frank...I'm using the merge to HDR in Photoshop...and I got the feedback earlier that I should go ahead and use the RAW images (did that tonight). As I don't know that I have the eye to discern the difference between 8/16/32 bit images, can you tell me what I should look for?

Let me see if I understand then...I open my 3 images in Merge to HDR & make it 32 (or 16) bit. Immediately next (do I have this correct?) I open the image in Photoshop and save it (as what? .tiff? ) At this point, how can I open it as a RAW image (I understand about the toning in RAW).
Is it still recognized as a RAW file?

Your last sentence, Frank, indicates that you know VOLUMES more than I do...I have no idea what "holes in the tone palette" means! That's most likely for the discerning eye I hope to develop someday!

You and Taffy are brilliant photographers and exceedingly gracious with your time and attention to the needs of others...I'm most grateful! My "style" (if I have one) is more photo journaling my daily life, but I'd like to elevate my skills, in no small part for having been exposed to the talented people on 365. Again, you have my appreciation and many thanks!
May 3rd, 2014
@Weezilou @frankhymus Thanks for such kind comments! I need to clarify what I was asking...when I bracket my shot, I always have the choice of how much I want to adjust the f-stop. So, I can choose .3 to .7 on up to 3.0 on my camera. But earlier than that decision, I can either do +2 (and then choose the amount) or -2, for example.
Frank, what's the difference in this choice?
Thanks to both of you!
May 3rd, 2014
@taffy You should never bracket by f/stop for HDR, only exposure. Why? The variation in depth of field can severely mess up the merge badly.

Also, I think what you are referring to might have to do with the EV "increment" granularity and the absolute width of the particular bracket.

There's no absolute rule or guideline about what the difference should be, but with a three bracket, a 2EV difference (0, -2, +2) is a good place to start, and for a five bracket 1EV (0, -2,-1,+1, +2). You just have to get a feel for your camera and the light situation. Or shoot several brackets just to be sure you have one that will work OK.
May 4th, 2014
@Weezilou When I merge images to HDR in Photoshop, I will typically use four or five images; unaltered RAW is best (after opening through Camera RAW), but I have also used the accompanying JPGs the camera shoots. As you pointed out, results vary.
I've had bracket spans in my HDR merges that went something like -1.5, 0, +.5, +2.0 to get what I wanted. There are times when two images will work perfectly. Again, playing with the images in the merge window will give you the image you are looking for. My Day051 ( http://365project.org/cabezacoco/365/2014-04-14) is an example of a three-image process using shutter speed to change exposures.
@frankhymus Is absolutely correct - keep the f/stop at the same setting and vary the shutter speed (or ISO if you are feeling adventurous).
When I get the result from the merge, Photoshop opens the image in 16-bit. To save it as a Photoshop RAW, you have to change the mode to 8-bit before you "Save As..." I find 16-bit uncompressed TIFFs work fine.
HDR Toning - under the "Image > Adjustments" menu gives fun options that you can customize and save. My Day041 ( http://365project.org/cabezacoco/365/2014-04-04) and Day056 ( http://365project.org/cabezacoco/365/2014-04-19) images are an example of the HDR toning tool.
Have fun out there.
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