How to get extreme values from a falsecolor image

Shit, it appears that the –a option fell off the wagon when falsecolor was converted from a csh script to a Perl script. I swear it used to be there. Am I losing my mind? This is entirely possible. OK, ok, bad info there. Sorry about that one, Vaib.

Now then, the pextrem deal. What do you mean it doesn’t take an hdr file? That’s precisely what it does. Here’s what that should look like:

$ pextrem pass2-v2lux.hdr
99 511 0.000000e+00 0.000000e+00 0.000000e+00
4 232 9.960938e-01 9.960938e-01 9.960938e-01

IOW, you call pextrem, give it an hdr image, and it returns the pixel coordinates (x,y) and radiance (Rr,Rg,Rb) of the low and high pixels. What’s happening when you try this?

···

From: Vaib [mailto:[email protected]]
Sent: Wednesday, February 05, 2014 10:25 AM
To: Radiance general discussion
Subject: Re: [Radiance-general] How to get extreme values from a falsecolor image

Thank you Rob.

Am I doing it wrong? -a option is a "bad option" :slight_smile: Not valid argument I mean..
$ falsecolor -i foo.hdr -s 1000 -n 10 -l Lux -a > bar.hdr

And pextrem doesn't take HDR file. I have to work with HDR, as it has conversion libraries in Java.

Vaib

On 5 February 2014 17:50, Guglielmetti, Robert <[email protected]<mailto:[email protected]>> wrote:
Hi Vaib,

A couple of things:

Thing One: there is an –a option, which “autoscales” the max value for the scale to peak at the max value found in the image.
Thing Two: yes, you can use pextrem to get the min and max values (in Rr,Rg,Rb) printed to the command line.

- Rob

From: Vaib [mailto:[email protected]<mailto:[email protected]>]
Sent: Wednesday, February 05, 2014 9:39 AM
To: Radiance general discussion
Subject: [Radiance-general] How to get extreme values from a falsecolor image

Hello everyone,

Falsecolor's documentation states that "The −e option causes extrema points to be printed on the brightest and darkest pixels of the input picture."

Is there any way to output (not print on image) the extrema values? This could be helpful in appropriately scaling the "scale".

Thank you!

Best regards,
Vaib

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