HDR question

12sndsgood · May 11, 2011

so a friend of mine posted up his first HDR attempt. the pics were underexposed, looked a bit dull and flat. i believe this was caused by the fact that all three shots that he merged were underexposed. so someone chimed in that they were not HDR for this fact. because they weren't showing off the highs and lows. it was more just a combination of low light photos. my take on it is that it is an underexposed HDR and that it can still be HDR because you are using a broad range of underexposed shots. anyone care to chime in with there opinions.

o hey tyler · May 11, 2011

12sndsgood said:
so a friend of mine posted up his first HDR attempt. the pics were underexposed, looked a bit dull and flat. i believe this was caused by the fact that all three shots that he merged were underexposed. so someone chimed in that they were not HDR for this fact. because they weren't showing off the highs and lows. it was more just a combination of low light photos. my take on it is that it is an underexposed HDR and that it can still be HDR because you are using a broad range of underexposed shots. anyone care to chime in with there opinions.

Well, if there's not enough exposures to properly get every part of the scene well exposed w/o blowing out the sky, or underexposing the ground, it's not really a HDR photo in my opinion. For it to have HIGH DYNAMIC RANGE, the dynamic range of the photograph should be fully represented. Instead, it just sounds like your friend has a mostly underexposed merged photo. If you have a broad range of underexposed shots, there's nothing for your software to pull from that will properly expose the dark areas. That's just my take on it, but I don't shoot HDR shots that much. I just am familiar with the process.

Trever1t · May 11, 2011

I would think not. HDR = High Dynamic Range and a series of under-exposed shots do not a HDR make.

Judobreaker · May 11, 2011

If you have 3 photo's which are all three underexposed it can possibly be an HDR photo, but it might also not be.
A true HDR photo has a wider range of correct exposure than a normal photo which means you can have very dark and very light areas both exposed correctly in a single photo.
To achieve this however you will need several photos that together contain the information needed for the correct exposures.
In other words, you'd need at least one photo for the low light exposure (overexposed), at least one for the middle light exposure (normally exposed) and at least one for the high light exposure (underexposed) to get all these correctly in the HDR photo.

If however you use only underexposed photos you will be missing a part of the middle light exposure and all of the low light exposure so these parts of the photo will not be correctly exposed in the HDR image.
Assuming you have three differently exposed photos which are all in a certain grade underexposed you'll have a higher range in the high light exposure parts of the image so technically it will be an HDR image (though the result is probably not extremely pleasing as the low light information is missing).
If you use three photos with the exact same exposure it is not an HDR image no matter what you do with it as you do not add any extra information with the second and the third image.

I hope this helps you understand HDR a bit.

12sndsgood · May 11, 2011

heres my thinking and this may come out wrong. taking the thoughts from my head and getting them into words is not my strong suite. here goes. a high dynamic range im thinking as some say the brightest lights and the darkest darks. now if he is taking the brightest brites of the photos he has and taking the darkest darks of the photo he has he is getting an hdr image of what he shot. it may not be the brightest brites possible but he has gotten the brightest brites of the photos shot. as in he has more range then a standard single photo. but not as much range as what is possible.

not saying anyone above is wrong, this is just my take on it and i'd like to learn more on the subject.

Judobreaker · May 11, 2011

Well, you put it a bit weird but I think you meant the right thing. ^^
If you take the brightest bright from the darkest photo and the darkest dark from the brightest photo you will end up with a photo with a lot more details because nothing will be under- or overexposed.