hdr imaging doubts - evalglare

Sir,
I had gone through a pdf glare analysis with evalglare, and i hav met with
some problems.
1.As evalglare software requires hdr images of 800x800 pixels, i tried to
get the pixel information using getinfo in DOS window from the START
button-> run->cmd. And while using pfilt command to divide x and y by a
number, it says pfilt is not recoznised as an internal or external command.
Is there another command to resize the image that can be used with DOS
window?
2. How shall i install the evalglare application? When i run evalglare
application by right clicking the setup file,a plain dos screen appears.How
shall i start with it?
3. Will evalglare work well with hdr images other than fish-eye?
Please help me to solve these issues.
Thankyou

Hi Nithya,

I think noone answered this so far.

1.As evalglare software requires hdr images of 800x800 pixels, i tried to get the pixel information using getinfo in DOS window from the START button-> run->cmd. And while using pfilt command to divide x and y by a number, it says pfilt is not recoznised as an internal or external command. Is there another command to resize the image that can be used with DOS window?

Pfilt is a program coming with Radiance (www.radiance-online.org). It allows you to filter images in Radiance RGBE format, an HDR image format storing a wide range of radiance (or, sometimes, irradiance) values maintaining acceptable file sizes. However, it applies algorithms to the file that go beyond scaling the image size. I would thus propose to use pcomb instead, again, part of Radiance.

Both tools provide a command-line interface, no graphical user interface. The syntax for pcomb to generate a 800 by 800 pixel version of big.hdr would be
pcomb -x 800 -y 800 -o big.hdr > small.hdr

The -o will revert any exposure-adjustments that may have been applied to your image before. small.hdr would be the image to be processed by evalglare.

2. How shall i install the evalglare application? When i run evalglare application by right clicking the setup file,a plain dos screen appears.How shall i start with it?

Evalglare is just one program that should be located in a directory included in your operating system's search path. No need for any kind of "installer".

3. Will evalglare work well with hdr images other than fish-eye?

Yes. However, you need to know the vertical illuminance than, which can be calculated from the pixel values in case that you have a 180 degrees fisheye.

I guess you are working in some Windows environment. I have no experience with this, so my answers are pretty generic. You will need to know how to work on the command-line if you want to start using evalglare and Radiance HDR tools. This is not specific to HDRI, but to knowing your operating system. Many do not find Windows to be a very comfortable environment for such applications, I would rather go with a Linux or Mac OS installation, however it is not impossible.

Good luck, cheers, Lars.

I hadn't noticed before that this question is posted to the HDRI list, which may have a limited number of readers who are also using evalglare on Windows. It might be worthwhile to post your questions #1 and #2 to the radiance-general mailing list in this case. Those questions have more to do with successful use of evalglare and Radiance in Windows than they are specific to HDRI. To add to Lars' answer for question #3, please check this link:
http://radiance-online.org/pipermail/radiance-general/2012-February/008353.html

Regards,
Chris

ยทยทยท

-----Original Message-----
From: Lars O. Grobe [mailto:[email protected]]
Sent: Saturday, October 05, 2013 12:07 PM
To: High Dynamic Range Imaging
Subject: Re: [HDRI] hdr imaging doubts - evalglare

Hi Nithya,

I think noone answered this so far.

1.As evalglare software requires hdr images of 800x800 pixels, i tried
to get the pixel information using getinfo in DOS window from the
START button-> run->cmd. And while using pfilt command to divide x and
y by a number, it says pfilt is not recoznised as an internal or
external command. Is there another command to resize the image that
can be used with DOS window?

Pfilt is a program coming with Radiance (www.radiance-online.org). It
allows you to filter images in Radiance RGBE format, an HDR image format
storing a wide range of radiance (or, sometimes, irradiance) values
maintaining acceptable file sizes. However, it applies algorithms to the
file that go beyond scaling the image size. I would thus propose to use
pcomb instead, again, part of Radiance.

Both tools provide a command-line interface, no graphical user
interface. The syntax for pcomb to generate a 800 by 800 pixel version
of big.hdr would be
pcomb -x 800 -y 800 -o big.hdr > small.hdr

The -o will revert any exposure-adjustments that may have been applied
to your image before. small.hdr would be the image to be processed by
evalglare.

2. How shall i install the evalglare application? When i run evalglare
application by right clicking the setup file,a plain dos screen
appears.How shall i start with it?

Evalglare is just one program that should be located in a directory
included in your operating system's search path. No need for any kind of
"installer".

3. Will evalglare work well with hdr images other than fish-eye?

Yes. However, you need to know the vertical illuminance than, which can
be calculated from the pixel values in case that you have a 180 degrees
fisheye.

I guess you are working in some Windows environment. I have no
experience with this, so my answers are pretty generic. You will need to
know how to work on the command-line if you want to start using
evalglare and Radiance HDR tools. This is not specific to HDRI, but to
knowing your operating system. Many do not find Windows to be a very
comfortable environment for such applications, I would rather go with a
Linux or Mac OS installation, however it is not impossible.

Good luck, cheers, Lars.

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