HDR Problems

[SimonTALM]

I use CS3 to create the HDR as I find it does a better job of merging handheld exposures at 5FPS

However, if I tone map using Photomatix plug in and then convert to 16bit I always seem to have white spots appearing in the shaddow areas of the image.

If I convert to 16bit and then tone map I am free of white spots but at 100% the colours in the image appear blocky with sudden harsh changes to the colour.

What am I doing wrong?

 

[SimonTALM]

Bump

 

[Chappers]

HDR is designed to handle scenes with a larger than normal dynamic range. These are best shot RAW ( because there is more data in RAW) and about 2-3 stops apart.

These are then merged and aligned and the data converted to 32 bit, which shows more range. This can then be adjusted for the real world of 8 bit.

I suspect you are trying to use the HDR system to give results it was never designed to do, hence the unpredictable nature of your resultant images

 

[SimonTALM]

I'm using 3 Raw shots at +1 0 & -1 ev via CS3's Merge to HDR facility and that works OK giving me a 32bit image, it's just when I try to get to 16bit or 8bit and tone map things don't work :shrug:

 

[Chappers]

Try using Local Adaption

 

[SimonTALM]

Cheers, I will do when I get home, When should I do this before or after Tone Mapping?

 

[Chappers]

A very quick start to finish technique based on Kevin Ames article in Photoshop User

In CS3 select Automate >Merge to HDR.
Select your images and let Photoshop align the layers and do it's job
When it gets to the preview stage, switch to 16 bit and set the white point. It's important to get this part right as it will affect the conversion. Fortunately as the process of getting here is automatic, you can start again fairly easily if it all goes wrong

From the HDR conversion dialogue box, select "Local Adaption" it's the last one on the list.And open the toning curve and histogram display.

Now pick the left hand point of the curve and move it horizontally until it almost touches the left hand part of the histogram. Repeat this with the right side.

You can also do some curve adjustment here if yiou want , but I would suggest you leave that alone for the moment.

When happy press OK.

I think you'll need to practice on a few images to get the exact workflow down. Each has its own individual requirements, but to make sure you get the white point stage right as if not it's back to the start