HDRI Digest, Vol 70, Issue 4

Dear Lars:

Thank you for your proposed alternatives. Webhdr is a great, user friendly tool and I was not aware of that.
I have one more question regarding the calibration.

V. Kumaragurubaran and M. Inanici have proposed two methods for calibration. one is based on measuring the absolute luminance of the graycard and the other one is based one measuring the illuminance at the camera level in the scene that they suggest it for special cases such as sun and sky capture.

I am doing daylight research in an office area with alternative shadings (artificial lighting is off during the study).
Is using the Illuminance calibration that utilizes captured illuminance of the camera level with the handhold illuminance meter (proposed in hdrscope) a correct way of calibrating the HDR photos In my case?

Regards
Fatemeh
M.ARCH
UNIVERSITY PUTRA MALAYSIA

···

On Sat, 19 Apr 2014 12:00:00 -0700, [email protected] wrote:

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   1. Re: HDRI Digest, Vol 70, Issue 3 (gs33070)
   2. Re: HDRI Digest, Vol 70, Issue 3 (Lars O. Grobe)

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Message: 1
Date: Sat, 19 Apr 2014 12:29:04 +0800
From: gs33070 <[email protected]>
To: <[email protected]>
Subject: Re: [HDRI] HDRI Digest, Vol 70, Issue 3
Message-ID: <[email protected]>
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On Thu, 17 Apr 2014 12:00:00 -0700, [email protected] > wrote:

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Today's Topics:

   1. Re: HDR for Glare Analysis (Lars O. Grobe)
   2. Re: HDR for Glare Analysis (Gregory J. Ward)

----------------------------------------------------------------------

Message: 1
Date: Thu, 17 Apr 2014 12:14:35 +0200
From: "Lars O. Grobe" <[email protected]>
To: High Dynamic Range Imaging <[email protected]>
Subject: Re: [HDRI] HDR for Glare Analysis
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hi Fatemeh,

I do not know wether the dynamic range of the raw images you get from
your camera matches the requirements of what you intend to do with
those
images. The wide dynamic range in typical daylid scenes led folks
here
to use exposure series. About the software, I have some doubts that
Adobe will tell you about the internals of their HDR code. So it will
be
difficult to get support or any information about the meaning of
pixel
values in the resulting images. Does Adobe claim the resulting HDR
images to have physically correct values?

Cheers, Lars.

Hi there:
I have a question that concerns HDR photo and Glare analysis.

Can I use Adobe Photoshop CC (which has the Camera Raw plugin) to
prepare my HDR images?
after that calibrate it with the use of HDRSCOPE that is proposed by
Mehlika Inanici. Instead of Photosphere?
Regards
Fatemeh
M.Arch
University Putra Malaysia

------------------------------

Message: 2
Date: Thu, 17 Apr 2014 08:37:18 -0700
From: "Gregory J. Ward" <[email protected]>
To: High Dynamic Range Imaging <[email protected]>
Subject: Re: [HDRI] HDR for Glare Analysis
Message-ID: <[email protected]>
Content-Type: text/plain; charset=us-ascii

While you *might* be able to use Adobe's CameraRAW processor to
convert the original images to JPEGs, later to be combined using
hdrgen or similar, Lars is right that Photoshop itself does not
maintain absolute photometric calibration throughout its processing.

Adobe actually hired me to improve their HDR image merge process, so
CS3 and later (I think) derive a camera curve and maintain correct
relative values in the images, similar to Photosphere, but I never
convinced Adobe to include calibration information in their output.
So, you would need to include a gray card or something whose
luminance
you measured when you captured the image and use this to correct the
final output using a scale factor. (It is usually a good idea to do
this, anyway.) The procedure for doing this can be found on Mehlika
Inanici's site, and also in other posts to this mailing list.

Cheers,
-Greg

From: "Lars O. Grobe" <[email protected]>
Subject: Re: [HDRI] HDR for Glare Analysis
Date: April 17, 2014 3:14:35 AM PDT

Hi Fatemeh,

I do not know wether the dynamic range of the raw images you get
from your camera matches the requirements of what you intend to do
with those images. The wide dynamic range in typical daylid scenes led
folks here to use exposure series. About the software, I have some
doubts that Adobe will tell you about the internals of their HDR code.
So it will be difficult to get support or any information about the
meaning of pixel values in the resulting images. Does Adobe claim the
resulting HDR images to have physically correct values?

Cheers, Lars.

Hi there:
I have a question that concerns HDR photo and Glare analysis.

Can I use Adobe Photoshop CC (which has the Camera Raw plugin) to
prepare my HDR images?
after that calibrate it with the use of HDRSCOPE that is proposed
by Mehlika Inanici. Instead of Photosphere?
Regards
Fatemeh
M.Arch
University Putra Malaysia

------------------------------

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End of HDRI Digest, Vol 70, Issue 3
***********************************

Thank you guys for your reply:

I think I will go for Greg solution, including a gray card or something
whose luminance that I captured the image and use this to correct the
output using a scale factor.
I wish there was a Photosphere for windows also.
cheers
Fatemeh

------------------------------

Message: 2
Date: Sat, 19 Apr 2014 16:25:31 +0200
From: "Lars O. Grobe" <[email protected]>
To: High Dynamic Range Imaging <[email protected]>
Subject: Re: [HDRI] HDRI Digest, Vol 70, Issue 3
Message-ID: <[email protected]>
Content-Type: text/plain; charset=us-ascii

Hi Fatemeh,

are you aware of alternatives such as pfstools and webhdr?

Cheers, Lars.

------------------------------

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End of HDRI Digest, Vol 70, Issue 4
***********************************

Just a request to make reading posts easier -- please do NOT include an entire digest with your post.

Write what you have to say at the beginning, and paste in whatever *relevant* information people might want who haven't been following the recent conversation.

As a general rule, keep it short and sweet and avoid a lot of redundant information.

Thanks!
-Greg

···

From: gs33070 <[email protected]>
Subject: Re: [HDRI] HDRI Digest, Vol 70, Issue 4
Date: April 20, 2014 9:16:36 PM PDT

***********************************

Dear Lars:

Thank you for your proposed alternatives. Webhdr is a great, user friendly tool and I was not aware of that.
I have one more question regarding the calibration.

V. Kumaragurubaran and M. Inanici have proposed two methods for calibration. one is based on measuring the absolute luminance of the graycard and the other one is based one measuring the illuminance at the camera level in the scene that they suggest it for special cases such as sun and sky capture.

I am doing daylight research in an office area with alternative shadings (artificial lighting is off during the study).
Is using the Illuminance calibration that utilizes captured illuminance of the camera level with the handhold illuminance meter (proposed in hdrscope) a correct way of calibrating the HDR photos In my case?

Regards
Fatemeh
M.ARCH
UNIVERSITY PUTRA MALAYSIA