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Thread: Hdr

  1. #1

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    Chris

    Hdr

    My first attempt using a bracket of three exposures, +1.7, on, -1.7 EV. I used Surrealism with a variety of layer masks to oush and pull the colors and textures. Since I have nothing in my background to compare it to, I'm going to need some feedback from you folks that do a lot of HDR.

    As you can tell by the output, I am not much into real super exaggeration, but do like the ability to layer up a higher degree of contrast.

    Hdr

  2. #2
    CBImages's Avatar
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    Re: Hdr

    Hi Chris

    I'm no expert on HDR but I have played about with it and realised the finished result depends quite a lot on how you blend the exposures together, I haven't done it manually but have used the HDR Pro in Photoshop and I have also used Photomatix. In my opinion Photomatix gives you more flexibility but once your images have been blended they do need a lot of processing to get the best from them.
    I think the true power of HDR lies in being able to bring out the detail in the shadows while retaining detail in the highlights, you can do that to a greater or lesser extent dependent upon your individual tastes. I think your image could do with more detail being brought out in the shadow areas, as it stands it looks like a very sharp, traditional single exposure.
    It also looks to have a yellow cast in a couple of areas, I have got that in a few HDR images I have created but can usually get rid of it when editing the image after the exposure have been blended. That is one of the keys to HDR in my opinion - edit them after blending to achieve the desired effect.


    Regards

    Chris

  3. #3

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    Re: Hdr

    It probably does have a slight yellow cast, but it was shot just as the sun broke the horizon and it was a really yellow sun. I kind of like the warmth but will look again to see if there is another cast in there not intended. Thanks for your input.

  4. #4

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    Alan Pezzulich

    Re: Hdr

    Hi Chris,

    I agree that your shadows lack detail. You really need HDR software to produce a hight quality image.

    You are using three layers and blending them using layer masks. If you blend an area of bricks using layer masks you will get the entire area lighter or darker. HDR software works differently. The first step in HDR processing is to combine the three images into a single image. The computer reads each image and also reads the EXIF data to determine an absolute value for each color channel. The software compares the value from each photograph and chooses which one to use in the HDR image. The original photos are either 16 bit (RAW) or 8 bit (Jpeg). The HDR file is 32bit.

    The HDR file needs to be tone mapped. The software contains proptiatary algorithms which change the intensity pixel by pixel. These algorithms are what makes the shadow details pop out. The propriatory algorithms are based on some very sophiosticated theories on how the eye sees. When adjusting a area containing bricks the red bricks and the mortar are given different adjustments to make them stand out. All of the brick are not given the same adjustment. If there is a dark area to the left of the bricks and a light area to the right of the bricks the algorithm will make the bricks on the left lighter and the bricks on the right darker. This allows the computer to darken the adjacent light area and lighten the adjacent dark area. THe human eye will not notice the variation in the bricks but will perceive the brick borders as correct.

    Even after using all of the magic of the HDR software it may still be necessay to correct some colors and othe things in Photoshop. Skintones in images produced by the HDZR software will probably need to be fixed.

    Alan

  5. #5

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    Have a guess :)

    Re: Hdr

    Quote Originally Posted by MiniChris View Post
    My first attempt using a bracket of three exposures, +1.7, on, -1.7 EV.
    Hi Chris,

    From a technical perspective, when you have a camera that will capture around 12 stops of dynamic range in a RAW exposure at base ISO - and your final image (as presented here) is going to be limited to around 6 stops of DR - then a +/- 1.7 stop bracket really isn't going to do a heck of a lot.

    Looking at the image, I can't really see anything that would require HDR techniques anyway, as it's mostly relective, with - perhaps - a little backlighting from the sky portion. If it were me, I'd be inclined to simply expose the scene to the right of the histogram, and reveal shadow detail with the shadows slider; adjusting midtones to taste using the brightness slider in ACR, or using a levels layer (or possibly curves) in Photoshop.

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