Panomundo

3D Photography by Brian Greenstone, Austin TX

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HOW TO: The Process of Making a Pano

Section 4: Converting RAW Files to TIFF

There are several things that need to be done to your RAW images when converting them to TIFF's, especially when using fisheye lenses. Here are the steps that I recommend:


Open Files with Photoshop's RAW Importer Dialog

There are many parameters that we need to set in the Photoshop RAW importer dialog. The first is the white balance. Hopefully there will be something grey or white in your scene that you can get a good white balance off of. Select the eye dropper tool and click on something white. If it beeps, then that white pixel is too bright, so choose another area where it's slightly grey:

Here I picked a white pixel one the door to use for white balance.


At this point you may also want to tweak your exposure settings either by hand or by clicking the Auto feature. You'll also want to select 16 Bits/Channel in the Depth pop-up menu. Working in 16-bits for these early stages will preserve the integrity of the pixel data as we mess with it.

Now we need to do some lens tweaking, so click on the Lens tab. Here we need to set the Chromatic Aberration and Vignetting values. To set a good Chromatic Aberration value, zoom in on a section of your image that's near the outer 1/3rd of the fisheye image where chromatic aberration is strong. Now, just fiddle with the Fix Red/Cyan and Fix Blue/Yellow sliders to make the color shifting as minimal as possible. Some lenses may require that you move these sliders quite far.

Before Chromatic Abberation correction - note the red and cyan lines.


After Chromatic Abberation correction


The Vignetting sliders will adjust for brightness falloff at the edges of any image, and images shot with fisheye lenses tend to have sever vignetting. We need to equalize this now so that we don't have noticable seams in the stitched panorama. PTGui Pro has a built-in feature for removing vignetting, but it is still a good idea to do as much of the work here as possible. It is often difficult to tell when you've got it set correctly, but as long as you're in the ballpark you should be fine.

Before Vignetting correction


After Vignetting correction


Once you've set good Vignetting and Chromatic Aberration values, you'll want to save this lens setting for future use because it's always the same on every shot you shoot with that lens. Click on the Settings pop-up menu and save it there. You'll need to reset the white balance and exposure for each panorama, but the vignetting and CA values will remain constant.


Cleaning up the Image

A great utility for digital photos is a neat little plug-in called Noise Ninja. This thing can clean up noise without making images fuzzy like the Photoshop Despeckle filter does, and it works much better than any of the newer Photoshop Noise filters. It's pretty much magic in my opinion, and I process all of my digital photos through Noise Ninja because the results are astounding! You either download noise profiles from their web site, or create your own noise profiles for your camera. The noise profiles tell Noise Ninja how much noise your specific camera model generates at various ISO settings. Once you have a noise profile for your camera, it automatically loads that up each time you pass it a photo to it.

Here is a comparison showing how Noise Ninja can improve your shots:

Image before Noise Ninja

Flawless image after Noise Ninja


The Noise Ninja filter dialog has lots of options, so you can easily customize things if you need, but I never touch anything. I just let the noise profiles for my camera take care of business:


Tweaking the Image

After you've run your image through Noise Ninja it is best to not do any other tweaks at this point. Saturation is probably the only safe thing to tweak at this point, but do not tweak the sharpness or anything else like that now. Those things are done on the final stitched pano.

If you shot your images in portrait mode you'll probably want to rotate them 90º at this time. That just makes working with them in PTMac / PTGui a little easier since you don't have to set the Roll values of each image. Before saving the image you may also want to knock it down to 8 Bits/Channel. Some people like to work entirely with 16-bit images, but I've never found any benefit with it for stitching panos which have to be 8-bit in the end anyway.

When you're ready to save, be sure to save it as a compressed TIFF file. TIFF's are lossless, so unlike JPEG's, no image integrity will be lost when you load the image in PTMac to work with it.


Repeat for all Shots

Now that you've processed one shot in your pano you need to do it for all the remaining shots. The best way to do this is to create a Photoshop "Action" that does the RAW Import, Noise Ninja filtering, etc., and then run a Batch (File->Automate->Batch) operation to have it apply the settings identically to all the images for the pano.

Here's my Photoshop Action for my Sigma 8mm lens:


And here's the Batch dialog...




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©2005-2009 Brian Greenstone