HDR technique using 4X5 film

[Nathan Potter]

Over the years I have occasionally taken multiple images using 4X5 film. Usually that consists of three exposure brackets, one centered and one each under and over at 1 to 2 stops. This for mostly scenes I thought were particularly unique at the time. Since these are principally chromes with rather crappy dynamic range I've recently had the thought of combining these using some kind of HDR technique to increase dynamic range. I've not fiddled with HDR software at all so have no experience with the technique.

My thought is to make three scans on an Epson 750 then move them to an HDR package such as Photomatix to combine and tweak, then move to PS for final tweaking. Would Photomatix be suitable for this?

I've not seen any references for doing this in large format so I wonder about a couple of issues. First can multiple LF images that have been scanned be adequately registered using a software package? Has anyone tried this? Second, I'd like to preserve decent resolution for say a 16 X 20 print, so what are the prospects for doing this?

Essentially I'm not after gaudy effects but would like to preserve the natural rendering found in mostly Fuji Astia chromes. I suppose the same technique could be used for B&W LF.

Any input would be very useful.

Nate Potter, Austin TX.

[rdenney]

This falls into the category of "any input" rather than "expert input".

The Photomerge software in Photoshop is accurate enough to align images in translation, but has more problems in rotation, in my experience. Given your overlap will be 100%, it might work better than in my case, where I was scanning and merging two 6x9 ends of a 6x12 image.

Read about stitching in the various threads on using stitching from DSLRs for scanning--that should provide more clues.

As to managing the tones during the merge into an HDR--I'll step aside and let others comment. My ideas on the topic are all theoretical.

Rick "curious" Denney

[Andrew O'Neill]

Could you not increase the dynamic range by pre-exposing in the field? I did this back in the 90's. You'd save money on film, too.

[drm]

You might consider doing a manual exposure blend in PS, instead of the usual hdr approach. You have complete control of the process and the result can be much more natural looking. Along with the traditional exposure blending through layer masks there is a more precise technique, exposure blending through a luminance mask which is a little more complex at first, but in reality it is much less work and produces better results.

[Peter De Smidt]

You are going to want to use Adobe's PhotoMerge to align the images. You can then save them as separate files. After that, you can use any HDR software that you like. You might as well give Photoshop a try, since you have it. Photomatix would certainly work too, and it should have a demo mode. If you do use it, try the exposure fusion method instead of true HDR, as it gives a much more realistic result.

I took a series of of 4x5 chromes with this in mind, but I haven't gotten around to actually doing it. The main issue will be if there is any subject movement between the frames.

I agree with Dean. If you go the manual route, luminosity masks in Photoshop would be the way to go.

[adam satushek]

I have blended scans from multiple negatives in PS to increase dynamic range. I used to do it more when I scanned on an Imacon, but with my current scanner it has not yet been necessary.

I prefer the manual method; open 2 (or 3) scans in photoshop, layer manually, add layer masks, and simply paint in the areas that are needed. I find this an easy method to open shadows and add detail to highlights. I have tried HDR in photoshop but I prefer the control this offers. I have not played with luminiosity masks....so cannot comment there.

[Ken Lee]

I tried Photomatix and thought most of it was gimmicky. Perhaps the "effects" are less appealing if we're looking for a classic Large Format look.

Photoshop lets us merge in a number of ways, as others have pointed out.

Did I miss something with Photomatix?

[Kirk Gittings]

I've been using Tony's luminosity masks for many years. They are quite effective for small adjustments, but for a boost say beyond about 2/3-1 stop in shadow areas, I think he will find it lacking. I know I do. It is worse for recovering highlights. HDR programs, as a means of exposure blending (rather than creating cartoonish effects), are getting much better-at least the ones I mentioned.

[Henry Ambrose]

If its about gaining some details in particular areas, blend it by hand. IE: If you're working to save a blown out or featureless sky you can simply transfer over the well exposed sky and a bit more of the edges, then erase, adjust opacity, curves, etc. until you get what you want. Its tedious but works well. I do it regularly with DSLR files. You can also scan the same piece of film with different scan settings to get "better" sections of the film to blend with the good overall exposure that's lacking something.

[Peter De Smidt]

I tried Photomatix and thought most of it was gimmicky. Perhaps the "effects" are less appealing if we're looking for a classic Large Format look.

Photoshop lets us merge in a number of ways, as others have pointed out.

Did I miss something with Photomatix?

Try Photomatix's Exposure Fusion.

Another tip is to get as good a non-hdr image as you can. Then use that to blend with your hdr image, using masks if needed.