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xAgNO3x In reply to tasteofchaos100406 [2009-03-25 06:42:21 +0000 UTC]

Nice, then send me a note in order to see what you did

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xAgNO3x In reply to SAMIGUY101 [2009-03-24 17:06:42 +0000 UTC]

Well... HDRi is the real word. It means High Dynamic Range Image. It's a technine that comes from many years ago, starting with Ansel Adams and his own method called the Zonal System which basically consist on measuring specific areas in the landscape and doing a relation between all the measured areas with a table that he also invented, where all the 16 stops availables in a film camera can hold from any scene. With that table, he visualized the picture before taking it and he said that the camera should show the photo after taking it. He said that like 40 years before digital, a paioneer, you see. After taking the pic, he went to his laboratory and revealed the picture by zones in order to get the maximum dynamic range achievable with a film camera. The problem was that the system worked perfect in black and white but not in color. And Ansel Adams is studyed in the books about the history of photography. A cool guy.

Digital cameras has no more than 5 stops of dynamic range, except for the latest ones (Nikon D700 has 9 stops, same like Nikon D3). All the digital photographs are called LDRi, which means Low Dynamic Range Image. I've discovered by myself, and I feel proud of it, a way to increase the dynamic range by taking several pictures in order to obtain detail in every area of the picture (shadows, midtones and highlights) by using a tripod and masking the photos in Photoshop, but, few months later, I found a program called Photomatix which does the process much more accurately than the manual one I was developing.

Photomatix applyes a technique called Tonemapping, which means that maps all the tones obtained from the superimposition of several shots in one single image, image which has 32 bits per channel. The problem here is that tehre is no monitor able to display more than 16.7 million of colors and a color spectrum no bigger than the holded byu the sRGB color profle excepts for some monitors (above 3K dollars) that can show even more colors than the Adobe ProPhoto Color Profile, which holds the wider gamut of colors, see this [link] for a comparisson chart between color profiles and their gamuts; you will see that also papers are measured in gamuts that beloings to color profiles. The rounded triangle below all the triangles in the chart is the L*a*b* coplor space, which holds all the spectrum that our eye can see which goes from CMY to RGB.

Okay, so we have only sRGB monitors that can display only 16.7 million of colors, which means 256 tonal values per channel (RGB) and 256 opacity values (alfa channel) resulting in something called RGBA, which is equal to the famous 24 bits bits true colors that you can find when setting up your monitor (23 with the alfa channel).

An HDRi has 32 bits per channel, which means 96 bits in total. Light years away from the initial 24 bits from the 100% of monitors in the market. So, a 32 bpc image (HDRi) cannot be seen properly in our monitors, and here is where ToneMapping comes handy becasue it maps out the image in some way that it's possible to see it in our monitors.

In terms of stops, and HDRi can hold unlimited stops, depending on how much shots you have done, but usually, with 3-5 shots is okay. So, any 5 stops digital camera will increase the dynamic range of a photo to 25 stops. I own a Nikon D700, so in my case are much more stops.

Our eye is capable to see much more stops and colors and we can say our eye see in L*a*b*. But our eye, cannot distinguish more than 70 shades of grey. A trained eye can see more than 400 shade of grey.

The other problem is that there is also no output for 32bpc imgaes (HDRi). Epson has released a type of ink which has micro crystals inside in order to reflect more light than the mere pigment, but it also cannot reach the 32bpc images and the paper is million of light years to represent such amount of colors and shades.

To get an idea, Film Cameras are able to hold 16 stops, most professional photographic papers (the ones used in traditional photography) goes up to 6.5 stops. The papers from the Epson HDR Ink goes much more, but I don't know exactly how much, because that info is almost impossible to get through the Internet. It also prints in 16bpc.

Basically, an HDRi is the result of a superimposition of the same shot at different exposures in order to bring catch all the detail possible in each area: shadows, Midtones and Highlights.

Get your camera, put it on a tripod and shot 3 photos: one at -2 EV (sub expossed), the second at 0 E.V. (normal Exposure) and +2 E.V. (over expossed) and merge them into HDR by using Photomatix, then apply the tonemaping and play with the controls in order to get the result you want. Upload to DA and send me a note, to see what you did

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SAMIGUY101 In reply to xAgNO3x [2009-03-27 21:57:56 +0000 UTC]

I made a copy of this and will read it again and see what I can do...thanks

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xAgNO3x In reply to MelRSmith [2009-03-24 08:06:09 +0000 UTC]

Uh, yeah! In fact, there was a big sorm after that. Many kilometers away from there, the wind lifted up a truck

Thanks for the and the comment. I love big clouds, by the way

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xAgNO3x In reply to dan2452 [2009-03-24 08:06:24 +0000 UTC]

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