Question about header information of HDRI

Hi,

I'm writing you concerning my current project.
I'm working for TechnoTeam company. Manyfacturer of imaging luminance measuring devices (camera photometer).
Our aim is to export our own image file format (pixel-wise HDR float values) into the Radiance rgbe file format.
The aim is to give radiance users access to the measured luminance information combined with our information about lens configuration (geometrical data).
This may of interest for the "glare" community when analyzing the glare using radiance tools.

Anyway, writing the rgbe information is no problem.

But what about the header structure of the radiance HDRI format?
I'm a little confused about it and can't find a documentation structure how it is organized?
Unfortunately I'm no radiance user for carrying out own radiance projects to study it?

With my best regards
Dipl.-Ing. Tobias Porsch
TechnoTeam Bildverarbeitung GmbH
Werner - von - Siemens - Strasse 5
98693 Ilmenau

···

----------------------------------------------------------------------------
Email: [email protected]<blocked::mailto:[email protected]>
Phone: +49 3677 4624 0

TechnoTeam Bildverarbeitung GmbH
Geschäftsführer: apl. Prof. Dr.-Ing. habil. F. Schmidt
Standort: Ilmenau
Handelsregistereintrag: Jena HRB 300912

Hi Tobias,

the file format is described in the Radiance documentation: http://radsite.lbl.gov/radiance/refer/filefmts.pdf
Please refer to pages 28ff.

It is great to know that you are implementing an export option - I had to do this manually in the past using pvalue :wink:

Cheers, Lars.

Well, you asked at the right place! The Radiance header format is simple, a set of newline ('\n') separated comments, some of which are of the form:

VARIABLE=value

A space may appear after the equals ('=') but rarely/never appears before it. Other lines in the header do not have this form, and may be anything. However, the first line identifying the file should be:

#?RADIANCE

The "RADIANCE" portion above is traditional, whereas the "#?" sequence is the so-called "magic number" for Radiance pictures. Below is a typical information header:

#?RADIANCE
CAMERA= NIKON CORPORATION NIKON D700 version Ver.1.03
Photosphere created HDR image from '_DSC7719.JPG' '_DSC7720.JPG' '_DSC7721.JPG' '_DSC7722.JPG' '_DSC7723.JPG' '_DSC7724.JPG' '_DSC7725.JPG' '_DSC7726.JPG' '_DSC7727.JPG'
EXPOSURE=4.887013e-03
VIEW= -vtv -vh 51.765083 -vv 71.303574
OWNER= Greg Ward
CAPDATE= 2014:02:25 09:49:32
GMT= 2014:02:25 08:47:39
LATLONG= 46.948730 7.451972
FORMAT=32-bit_rle_rgbe

···

------
The header is terminated by an empty line (two newlines together "\n\n"). The following line after the empty line is very important, it contains the image resolution. It is typically in the form:

-Y ysiz +X xsiz

where xsiz and ysiz are the integer number of pixels in the image. This ASCII string is terminated by another newline ('\n'), immediately followed by the raster image data in the order indicated, Y (vertical) major sort, with Y values decreasing as measured from the bottom-left of the image. This is explained in more detail in the relevant section (pp. 28-35) of the Radiance file formats document, located here:

  http://radsite.lbl.gov/radiance/refer/filefmts.pdf

I see Lars has provided you with the same information. I hope this is enough to get you started. Please note the importance of the EXPOSURE= line in the header and the 179 lumens/watt standard conversion factor in creating a properly calibrated picture.

Let me know if you have further questions.

Best,
-Greg

From: Tobias Porsch <[email protected]>
Subject: [HDRI] Question about header information of HDRI
Date: July 23, 2014 8:27:01 AM PDT

Hi,

I'm writing you concerning my current project.
I'm working for TechnoTeam company. Manyfacturer of imaging luminance measuring devices (camera photometer).
Our aim is to export our own image file format (pixel-wise HDR float values) into the Radiance rgbe file format.
The aim is to give radiance users access to the measured luminance information combined with our information about lens configuration (geometrical data).
This may of interest for the "glare" community when analyzing the glare using radiance tools.

Anyway, writing the rgbe information is no problem.

But what about the header structure of the radiance HDRI format?
I'm a little confused about it and can't find a documentation structure how it is organized?
Unfortunately I'm no radiance user for carrying out own radiance projects to study it?

With my best regards
Dipl.-Ing. Tobias Porsch
TechnoTeam Bildverarbeitung GmbH
Werner - von - Siemens - Strasse 5
98693 Ilmenau
----------------------------------------------------------------------------
Email: [email protected]
Phone: +49 3677 4624 0

TechnoTeam Bildverarbeitung GmbH
Geschäftsführer: apl. Prof. Dr.-Ing. habil. F. Schmidt
Standort: Ilmenau
Handelsregistereintrag: Jena HRB 300912

Hi Thomas,

here is an example HDR header, as generated by Greg's hdrgen from a
sequence of exposure-bracketed JPGs:

--------------------- 8< --------------------
#?RADIANCE
EXPOSURE=4.335966e+00
VIEW= -vtv -vh 62.593719 -vv 49.021309
CAPDATE= 2012:01:04 11:47:01
CAMERA= Canon Canon PowerShot G12 version v.0
hdrgen created HDR image from 't5sjf7bvw227iifq.jpg'
'g5ux42y0sv6ijuaa.jpg' 'rdehbxsuy2deh237.jpg'
PRIMARIES= 0.6400 0.3300 0.3000 0.6000 0.1500 0.0600 0.3127 0.3290
FORMAT=32-bit_rle_rgbe

-Y 600 +X 800
--------------------- 8< --------------------

Apart from the 'VIEW=' line which should represent your camera's lens,
you'll need to make up a line to replace 'hdrgen created....'

I don't think there are any hard rules for this.

Regards
Axel

···

On 23 July 2014 16:41, Lars O. Grobe <[email protected]> wrote:

Hi Tobias,

the file format is described in the Radiance documentation: http://radsite.lbl.gov/radiance/refer/filefmts.pdf
Please refer to pages 28ff.

It is great to know that you are implementing an export option - I had to do this manually in the past using pvalue :wink:

Cheers, Lars.
_______________________________________________
HDRI mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/hdri

Hello again,

Thank you all for the many hints. I tried it out and it works now.
But anyhow I have a following problem now.

When I do insert the following lines to the header for the description of our used angular fish eye lens, radiance tools like 'evalglare' (the author is J. Wienhold) does calculate wrong results.

#?RADIANCE
FORMAT=32-bit_rle_rgbe
VIEW= -vta -vv 180 -vh 180 -vp 0 0 0 -vd 0 0 1 -vu 0 1 0
EXPOSURE=1.79e+02

-Y 1040 +X 1392

I do assume this is due to the fact that the circular field of view for our fish eye is just a part of the rectangular aspect ratio of the image.
For example the center of the circular view is x = 700px; y = 500px and the diameter = 450px.
Is it possible to tell this within the header?

Another possibility could be to crop the image according to this circular field of view. Is this possible?

Kind regards
Tobias

···

Von: Gregory J. Ward [mailto:[email protected]]
Gesendet: Mittwoch, 23. Juli 2014 17:57
An: High Dynamic Range Imaging
Betreff: Re: [HDRI] Question about header information of HDRI

Well, you asked at the right place! The Radiance header format is simple, a set of newline ('\n') separated comments, some of which are of the form:

VARIABLE=value

A space may appear after the equals ('=') but rarely/never appears before it. Other lines in the header do not have this form, and may be anything. However, the first line identifying the file should be:

#?RADIANCE

The "RADIANCE" portion above is traditional, whereas the "#?" sequence is the so-called "magic number" for Radiance pictures. Below is a typical information header:

#?RADIANCE
CAMERA= NIKON CORPORATION NIKON D700 version Ver.1.03
Photosphere created HDR image from '_DSC7719.JPG' '_DSC7720.JPG' '_DSC7721.JPG' '_DSC7722.JPG' '_DSC7723.JPG' '_DSC7724.JPG' '_DSC7725.JPG' '_DSC7726.JPG' '_DSC7727.JPG'
EXPOSURE=4.887013e-03
VIEW= -vtv -vh 51.765083 -vv 71.303574
OWNER= Greg Ward
CAPDATE= 2014:02:25 09:49:32
GMT= 2014:02:25 08:47:39
LATLONG= 46.948730 7.451972
FORMAT=32-bit_rle_rgbe

------
The header is terminated by an empty line (two newlines together "\n\n"). The following line after the empty line is very important, it contains the image resolution. It is typically in the form:

-Y ysiz +X xsiz

where xsiz and ysiz are the integer number of pixels in the image. This ASCII string is terminated by another newline ('\n'), immediately followed by the raster image data in the order indicated, Y (vertical) major sort, with Y values decreasing as measured from the bottom-left of the image. This is explained in more detail in the relevant section (pp. 28-35) of the Radiance file formats document, located here:

                http://radsite.lbl.gov/radiance/refer/filefmts.pdf

I see Lars has provided you with the same information. I hope this is enough to get you started. Please note the importance of the EXPOSURE= line in the header and the 179 lumens/watt standard conversion factor in creating a properly calibrated picture.

Let me know if you have further questions.

Best,
-Greg

From: Tobias Porsch <[email protected]<mailto:[email protected]>>

Subject: [HDRI] Question about header information of HDRI

Date: July 23, 2014 8:27:01 AM PDT

Hi,

I'm writing you concerning my current project.
I'm working for TechnoTeam company. Manyfacturer of imaging luminance measuring devices (camera photometer).
Our aim is to export our own image file format (pixel-wise HDR float values) into the Radiance rgbe file format.
The aim is to give radiance users access to the measured luminance information combined with our information about lens configuration (geometrical data).
This may of interest for the "glare" community when analyzing the glare using radiance tools.

Anyway, writing the rgbe information is no problem.

But what about the header structure of the radiance HDRI format?
I'm a little confused about it and can't find a documentation structure how it is organized?
Unfortunately I'm no radiance user for carrying out own radiance projects to study it?

With my best regards
Dipl.-Ing. Tobias Porsch
TechnoTeam Bildverarbeitung GmbH
Werner - von - Siemens - Strasse 5
98693 Ilmenau
----------------------------------------------------------------------------
Email: [email protected]<blocked::mailto:[email protected]>
Phone: +49 3677 4624 0

TechnoTeam Bildverarbeitung GmbH
Geschäftsführer: apl. Prof. Dr.-Ing. habil. F. Schmidt
Standort: Ilmenau
Handelsregistereintrag: Jena HRB 300912

Hello Tobias,

Unfortuately you will need to crop the image using some of the Radiance tools.

First you have to set the image exposure to 1 using ra_xyze,
ra_xyze -r -o in.hdr > exposure.hdr

Then use pcompos to do the cropping,
pcompos -x 450 -y 450 exposure.hdr X Y > cropped.hdr

Where X and Y are the anchor coordinates from the lower left corner of the image, if I recall correctly. I always end up having to tweak them until I get it correct. Some examples can be found by searching the mailing list.

Finally, this process will eliminate the view information you have, so it will need to be put back into the header.

Best,
Alstan

···

On Tue, 29 Jul 2014 08:01:00 -0400, Tobias Porsch <[email protected]> wrote:

Hello again,

Thank you all for the many hints. I tried it out and it works now.

But anyhow I have a following problem now.

When I do insert the following lines to the header for the description of our used angular fish eye >lens, radiance tools like 'evalglare' (the author is J. Wienhold) does calculate wrong results.

#?RADIANCE

FORMAT=32-bit_rle_rgbe

VIEW= -vta -vv 180 -vh 180 -vp 0 0 0 -vd 0 0 1 -vu 0 1 0

EXPOSURE=1.79e+02

-Y 1040 +X 1392

I do assume this is due to the fact that the circular field of view for our fish eye is just a part >of the rectangular aspect ratio of the image.

For example the center of the circular view is x = 700px; y = 500px and the diameter = 450px.

Is it possible to tell this within the header?

Another possibility could be to crop the image according to this circular field of view. Is this >possible?

Kind regards

Tobias

Von: Gregory J. Ward [mailto:[email protected]]

Gesendet: Mittwoch, 23. Juli 2014 17:57

An: High Dynamic Range Imaging

Betreff: Re: [HDRI] Question about header information of HDRI

Well, you asked at the right place! The Radiance header format is simple, a set of newline ('\n') >separated comments, some of which are of the form:

VARIABLE=value

A space may appear after the equals ('=') but rarely/never appears before it. Other lines in the >header do not have this form, and may be anything. However, the first line identifying the file >should be:

#?RADIANCE

The "RADIANCE" portion above is traditional, whereas the "#?" sequence is the so-called "magic >number" for Radiance pictures. Below is a typical information header:

#?RADIANCE

CAMERA= NIKON CORPORATION NIKON D700 version Ver.1.03

Photosphere created HDR image from '_DSC7719.JPG' '_DSC7720.JPG' '_DSC7721.JPG' '_DSC7722.JPG' >'_DSC7723.JPG' '_DSC7724.JPG' '_DSC7725.JPG' '_DSC7726.JPG' '_DSC7727.JPG'

EXPOSURE=4.887013e-03

VIEW= -vtv -vh 51.765083 -vv 71.303574

OWNER= Greg Ward

CAPDATE= 2014:02:25 09:49:32

GMT= 2014:02:25 08:47:39

LATLONG= 46.948730 7.451972

FORMAT=32-bit_rle_rgbe

------

The header is terminated by an empty line (two newlines together "\n\n"). The following line after >the empty line is very important, it contains the image resolution. It is typically in the form:

-Y ysiz +X xsiz

where xsiz and ysiz are the integer number of pixels in the image. This ASCII string is terminated >by another newline ('\n'), immediately followed by the raster image data in the order indicated, Y >(vertical) major sort, with Y values
decreasing as measured from the bottom-left of the image. This is explained in more detail in the >relevant section (pp. 28-35) of the Radiance file formats document, located here:

              http://radsite.lbl.gov/radiance/refer/filefmts.pdf

I see Lars has provided you with the same information. I hope this is enough to get you started. > Please note the importance of the EXPOSURE= line in the header and the 179 lumens/watt standard >conversion factor in creating a properly
calibrated picture.

Let me know if you have further questions.

Best,

-Greg

From:
Tobias Porsch <[email protected]>

Subject:
[HDRI] Question about header information of HDRI

Date:
July 23, 2014 8:27:01 AM PDT

Hi,

I'm writing you concerning my current project.

I'm working for TechnoTeam company. Manyfacturer of imaging luminance measuring devices (camera >>photometer).

Our aim is to export our own image file format (pixel-wise HDR float values) into the Radiance rgbe >>file format.

The aim is to give radiance users access to the measured luminance information combined with our >>information about lens configuration (geometrical data).

This may of interest for the "glare" community when analyzing the glare using radiance tools.

Anyway, writing the rgbe information is no problem.

But what about the header structure of the radiance HDRI format?

I'm a little confused about it and can't find a documentation structure how it is organized?

Unfortunately I'm no radiance user for carrying out own radiance projects to study it?

With my best regards

Dipl.-Ing.
Tobias Porsch

TechnoTeam Bildverarbeitung GmbH

Werner - von - Siemens - Strasse 5
98693 Ilmenau

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

Email: [email protected]

Phone: +49 3677 4624 0

TechnoTeam Bildverarbeitung GmbH

Geschäftsführer: apl. Prof. Dr.-Ing. habil. F. Schmidt

Standort: Ilmenau

Handelsregistereintrag: Jena HRB 300912