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FORUMS Post Processing, Marketing & Presenting Photos HDR Creation 
Thread started 01 Oct 2013 (Tuesday) 11:06
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Magic Lantern - Dual ISO readout

 
Osiriz
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Oct 11, 2013 13:56 |  #16

I am interested but also utterly confused by all this.

Kirkt, I'm not sure what you are doing there, but it looks better and more natural than any HDR I've ever done.

Got a link to some website with a "dummy explanation" on your technique?




  
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kirkt
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Oct 11, 2013 14:08 |  #17

There's a whole lot of stuff going on in these images - ironic, considering that they don't look like there's a lot going on in them!

I am still experimenting with the dual ISO approach, but it is similar in concept to the Zero Noise approach to exposure combination.

Search the forum in the HDR section for "Zero Noise" and start reading there. I put together a mini tutorial that outlines the concept and how to use it.

As far as getting a "natural" look - that takes a lot of different techniques, but is pretty straightforward. I usually start with opening the shadows while preserving the highlights - think screen blend mode with a luminosity mask. Then I enhance local contrast. Finally I restore color.

I'll keep adding to the thread, so stay tuned! If you have specific questions post them here and forum members will likely help you get the answers you are looking for.

kirk


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Osiriz
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Oct 11, 2013 15:37 as a reply to  @ kirkt's post |  #18

Thanks. I'm gonna do some reading :)




  
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kirkt
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Oct 11, 2013 16:39 |  #19

Here's a better (in my opinion) edit of this scene. I will leave all of my edits, bad or good, so we can all learn from my experiments!

kirk

IMAGE: http://kirkt.smugmug.com/Photography/Link-Share/i-XmXFPX3/0/X3/_MG_0001-2-X3.jpg

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kirkt
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Oct 11, 2013 21:43 |  #20

Here are some of the earlier noise(less) examples processed to final edit.

kirk

IMAGE: http://kirkt.smugmug.com/Photography/Link-Share/i-vzZbW3H/0/X3/_MG_0059-X3.jpg

IMAGE: http://kirkt.smugmug.com/Photography/Link-Share/i-5wNJgMT/0/X3/_MG_0083-X3.jpg

IMAGE: http://kirkt.smugmug.com/Photography/Link-Share/i-TT5D7Pq/0/X3/_MG_0073-X3.jpg

IMAGE: http://kirkt.smugmug.com/Photography/Link-Share/i-jQWkKhM/0/X3/_MG_0093-X3.jpg

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tzalman
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Oct 12, 2013 05:02 |  #21

Osiriz wrote in post #16363438 (external link)
I am interested but also utterly confused by all this.

Kirkt, I'm not sure what you are doing there, but it looks better and more natural than any HDR I've ever done.

Got a link to some website with a "dummy explanation" on your technique?

Here is a "nut shell", over simplified explanation.
Start with Kirk's description in his first post:

In essence, ML permits you to set up your exposure so that, for a single click of the shutter release, half of the sensor data is acquired at ISO 1 and the other half acquired at ISO 2. So, for example, you could use ISO 100 and 800 and shoot an scene that will read off half of the sensor at ISO 100 and the other half at ISO 800 (alternate sensor rows - actually alternating every two sensor rows to get the complete RGGB sensel block). This means you are capturing a single image, including motion blur and moving objects with two exposures simultaneously. The tradeoff is half vertical resolution, as the above quote indicates, as well as aliasing in the highlights and shadows, where the skipping of lines is more evident.

Imagine using the "pseudo HDR" of doing two conversions from a single Raw file, one of them with brighter shadows because you have increased "exposure" in the converter. The limiting factor is that increasing exposure in this way, digital brightening done in a computer, causes noise, so you can't push very hard. But raising the ISO in the camera also brightens the image and it is done analogically (electronically) which causes less noise. [Digression: Up to a certain point analog brightening always beats digital brightening. Going from ISO 100 to ISO 200 causes a very slight increase in noise, do it in the computer and you double the noise. But as you get into the higher ISOs each doubling of the ISO causes a greater noise increase, until (in the 5D2, for instance) going in the camera from ISO 1600 to ISO 3200 very nearly doubles the noise and the analog advantage is gone so the camera switches to digital brightening for the ISOs higher than 3200.] Until now the only way to get analog brightening for your HDR has been to take two or more shots at different ISOs. Magic Lantern lets you do it in one shot.

BTW, ML also does ISO bracketing which can be very useful in traditional multi-shot HDR, especially in low light situations, when bracketing speed might result in one of the exposures being very long and thus increasing blurring and ghosting. Of course the trade-off is slightly more noise than if all the exposures are at low ISO.


Elie / אלי

  
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kirkt
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Oct 12, 2013 10:40 |  #22

^^excellent! Thanks Elie.

Kirk


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kirkt
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Oct 15, 2013 21:39 |  #23

White van in sun, black car in shade, moving side by side with sunlit background. No noise reduction.

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IMAGE: http://kirkt.smugmug.com/Photography/Link-Share/i-P9D9qRk/0/X3/whitevanblackcar3-X3.jpg

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kirkt
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Oct 15, 2013 22:14 |  #24

And another.

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IMAGE: http://kirkt.smugmug.com/Photography/Link-Share/i-SWVJ2QC/0/X3/sunandshade-X3.jpg

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monty87
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Oct 19, 2013 00:16 |  #25

Kirkt, those are some amazing examples you have posted. I have avoided ML as I thought it was mostly for video use, but I definitely have to try this out now. Very anxious to try this in my new shiny 5dmk3.


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thedcmule2
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Oct 19, 2013 01:46 |  #26

@kikrt: whats going on with the power lines on the left though?




  
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kirkt
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Oct 20, 2013 22:14 |  #27

There is some aliasing when the dual iso CR2 is converted to a DNG - imagine trying to demosaic every two lines. The cr2hdr application appears to be getting development, so I can imagine that the process will get refined. But high contrast slightly off horizontal lines are sometimes a problem - my reducing the image size and compressing the file it doesn't help either. Moiré is also an issue in certain situations like this - again, same deal. If you go to the ML forum and read about the dual ISO concept you will appreciate why this happens.

Post your examples here and we can discuss your experiments.

kirk


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kirkt
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Oct 21, 2013 13:44 |  #28

In case you were not aware, Photomatix 5.0 is in beta and available for testing:

http://www.hdrsoft.com​/download/betas/pmp50.​php (external link)

The nice thing is, it reads single DNGs created by the ML dual ISO application cr2HDR, which is great. WIth the added useable dynamic range of these DNGs, it is nice to be able to integrate your trusty tools into the workflow. Here is an example of a dual IS DNG processed in Photomatix - no noise reduction! Horizon is a little crooked.

IMAGE: http://kirkt.smugmug.com/Photography/Link-Share/i-zt2HnQg/0/X3/_MG_0047_tonemapped-X3.jpg

kirk

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kirkt
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Oct 21, 2013 22:07 |  #29

I need to clean my sensor.

kirk


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kirkt
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Oct 21, 2013 22:54 |  #30

Another take on one of the test images - using the Contrast Optimizer in Photomatix 5 beta, with some finish in PS.

IMAGE: http://kirkt.smugmug.com/Photography/Link-Share/i-pNL9SfZ/0/X3/_MG_0080_tonemapped-X3.jpg

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Magic Lantern - Dual ISO readout
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