a Pseudo-HDR image

This is a follow up to my last post.

In that post, where I created an ‘HDR’ image from a single RAW file I lightly threw out the following statement:

I guess it isn’t technically an HDR, just the Tone Map.

That’s been eating at me ever since. First, was I full of it and Second, what did that really mean? So I read up on the process and here’s some clarification.

Generating an HDR in Photomatix is a two part process. The first generates the HDR from multiple images. After that is complete the merged image is Tone-mapped. Tone Mapping is where the ‘magic’ happens. Most of the enhancements happen there.

So when you generate an ‘HDR’ from a single image you’re creating a ‘Pseudo-HDR’ that is ready to be tone mapped. This is the explaination from the Photomatix User Manual (pg 7):

Photomatix Pro allows you to create a 32-bit HDR image from a single RAW file. To do this, open one RAW file using File >Open, and Photomatix will convert it into a pseudo-HDR image. It is important to note, through, that an image created with a single RAW file cannot really be considered High Dynamic Range. The important characteristic of this pseudo-HDR image is that it is unprocessed. Its dynamic range is not much larger than the range of an already converted file.

So 1- I’m not full of it and 2 – it means that when we’re processing a single image what we’re really doing (in the Photomatix view of the world) is generating a tone-mapped image.  When we’re processing from multiple images, the first step combines the multiple images, generating a single image with a wider exposure range, then we generate a tone-mapped image.

There is an additional feature within Photomatix – Exposure Blending. This feature allows you to blend images with multiple exposures without the HDR effect. Example – shooting a interior with windows where the outside exposure doesn’t match the inside. You could take an exposure that captures the inside of the room and another that captures the detail in the window and blend them into a single image. I tried that the first time I played with Photomatix just to see what it would do. I haven’t tried it since them. I’ll explore that more later.

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2 Responses to a Pseudo-HDR image

  1. clamroll says:

    You should really check out Lucis. It doesnt have half the control that photomatix does, but using some blending and masking in photoshop, you can get brilliant HDR images with less than half the headache of photomatix. It’s much faster too!

    Oh and incase you’re worried about the whole multiple images/single RAW thing… don’t be. Most of my best HDRs have been from single raw files. If you expose the file right, you can lift the 2-3 exposures you need with great ease.

    http://clamroll.wordpress.com/

  2. Scott says:

    Thanks for the tip. I’ll check it out. Kind of in that stage right now.

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