HDR from one image - help please

I wonder if (I'm sure that) someone can help with a little PS problem I have. I am trying to make an HDR/tone mapped type image from one original image. The way I am attempting it is this -
Create three different images in Light Room, one 4 stops under, one original exposure and one stops over. The three resulting images (jpegs) are saved in a separate folder.

I then go to PS and open File-Automate-Merge to HDR. The programme then proceeds but then comes up with the message that there was not enough dynamic range to create an HDR image. I would have thought that 8 stops is enough!

I know that people create images this way, so what am I doing wrong?

Roy Mathers wrote in post #4027778
I wonder if (I'm sure that) someone can help with a little PS problem I have. I am trying to make an HDR/tone mapped type image from one original image. The way I am attempting it is this -
Create three different images in Light Room, one 4 stops under, one original exposure and one stops over. The three resulting images (jpegs) are saved in a separate folder.

I then go to PS and open File-Automate-Merge to HDR. The programme then proceeds but then comes up with the message that there was not enough dynamic range to create an HDR image. I would have thought that 8 stops is enough!

I know that people create images this way, so what am I doing wrong?

Post Samples first

Roy Mathers wrote in post #4027778
I wonder if (I'm sure that) someone can help with a little PS problem I have. I am trying to make an HDR/tone mapped type image from one original image. The way I am attempting it is this -
Create three different images in Light Room, one 4 stops under, one original exposure and one stops over. The three resulting images (jpegs) are saved in a separate folder.

I then go to PS and open File-Automate-Merge to HDR. The programme then proceeds but then comes up with the message that there was not enough dynamic range to create an HDR image. I would have thought that 8 stops is enough!

I know that people create images this way, so what am I doing wrong?

you don't get 8 f-stops just for adjusting exposure in the development. The image remains the same, you have no more DR. PS detects this, and tells you it cannot increase DR if all 3 pictures have the same DR, just different exposure.

HDR from a single RAW file is not a true High Dynamic Range Image, and it's basically a pointless generating different exposures from the same file.

If you're gonna just tonemap the image, convert the RAW file directly into a 32-bit file and tonemap it (compress) it back to an 8/16bit file. you can do this in PS and Photomatix.

Also, the reason it's not working is because the Exif data for each generated 'exposure' is the same. HDR software works by reading the exposure information of each different exposure to determine how the values are merged.

Many thanks for your answers. They lead me on to two more questions. It seems that one of the reasons it's not working is because of the exif data - is there any way of removing the exif data so that the programme thinks they're three different files? Also, can you point me towards any tutorial that will tell me how to do tonemapping (or fake HDR)?. Thanks

GUI - I assumed that altering the exposure in, for instance, Lightroom was the same as different exposure in the camera?.

I think using the save for web option removes the EXIF data.

why is your underexposed image 4 stops under? it will introduce a lot of noise. from a single exposure, i never try the HDR process on more than 1.5 stops either side.

And how exactly do you do it?

i think with original RAW...save each exposure as a .tif (one under -2ev for example, one over +2ev and then the 0ev version. give each a slightly different filename (like append under2, over2 to them respectively).

That's more or less what I've done (except that I used jpegs an - and +4) - but I got the results outlined above.

http://www.fdrtools.co​m/fdrtools_basic_e.php
free and works fine doing what you want too do...

Roy Mathers wrote in post #4030317
I assumed that altering the exposure in, for instance, Lightroom was the same as different exposure in the camera?.

Software can't create detail that the camera didn't capture. As a matter of fact, one properly converted 16 bit tif will contain all the data contained in the RAW and you can get the same result from it with the Highlight/Shadows tool. Doing multiple conversions brings nothing new to the table, it's just another way of doing H/S.

In Photomatix there's one option called "Single File Conversion". You will need a RAW File for that though. This is doing then, what you want, even though it's still not real HDR.