Attempt at HDR
Posted: Mon Jun 02, 2008 2:59 pmI have not posted much in a while, so here is one I have done as an HDR. Not done very much of this sort of thing before so advice form some HDR guru's would be greatly appreciated.
Hi Geoff,
I assume you're using Photomatix because the image looks like it came thru Photomatix. Notice there is a lot of local contrast around the rigging of the yachts. The contrast in the sky ends up looking different on either side of a given piece of rigging. The mast on LHS is a particular example of this. If you adjust the top slider in Photomatix (I think it's called Strength) from the default (70% ?) down to about 25% - 30%, you will get rid of this obvious contrast differential. But this will tend to make the image look flatter. You've got to fiddle with strength and then with both highlight and shadow saturation to make it look right.
You've also got some chromatic aberation coming thru. Photomatix seems to exagerate any CA. So it's absolutely essential to get rid of it from the tiffs before you do the HDR generate. The best way to do this is in the raw conversion. Take the image up to 100% size and look for the CA (green and blue areas on edges of high contrast). Adjust the CA sliders in the raw convertor to eliminate the CA. Then apply the same parameters to all the images in the bracket. If you're starting from Jpgs, then I don't know what to suggest to get rid of CA. Apart from start with raw images.
The water doesn't look right. You need to select the checkbox that says to eliminate moving things. Try the two options here. Also the tone mapping always makes water too light so your reflections are too light. A reflection of anything is darker than the original, because some light is being absorbed. To correct for this, I take the tone mapped tiff and the best exposed original from the bracket into Photoshop and blend them together with opacity slider to bring the darker reflection into the image.
Sharpening at the wrong time can ruin the HDR. Don't let the raw converter or camera do any sharpening. You do the sharpening after you've made the tone mapped image.
There is no detail in the hot spots in the cloud. This means you ahven't got enough dynamic range in your bracket of shots. So you need to either increase the number of shots in the bracket or the EV difference between each shot. To get the sequence of exposures for an HDR, you need to get all the highlights in one shot and all the shadows in another and everything in between in the other shots. Clipping the highlights is particularly obvious whereas you can often get away with clipping the shadows.
I assume you are bracketing in your camera and using a tripod. You should be. I haven't been able to produce a realistic looking HDR if I haven't used a tripod.
I guess my last comment is that the idea of constructing an HDR image is to capture the high dynamic range, BUT to make the image look realistic. It takes alot of practise and tweaking of the various tone mapping parameters to make it look realistic.
Cheers
John