pcond -h and rpict

Hey folks - question about the "human" exposure response in rpict (ximage) versus pcond. When I render an image (call it "output.hdr") and display it in ximage, I hit the "h" key and the image gets redisplayed with the "human" exposure mapping. Then i take output.hdr and i put it through

  pcond -h output.hdr > output_cond.hdr

(now call the new conditioned file "output_cond.hdr") When i display "output_cond.hdr" in ximage, i get a different resulting image than when I viewed output.hdr in ximage and hit "h". The ximage "h" version of output.hdr is darker and has more contrast than the output_cond.hdr image. What's up with that?

thanks,

kirk

Hi Kirk,

Ximage using the 'h' command or the -e human option is more-or-less equivalent to pcond -c -s, but the -h option of pcond turns on acuity and veiling glare filters (-v and -a) that are not included in ximage. The veiling glare in particular can reduce the image contrast, especially around bright sources and objects. Also, pcond using foveal-size (1 degree) luminance samples, rather than pixels, and this can result in a different tone curve.

-Greg (waving his hands wildly)

···

From: Kirk Thibault <[email protected]>
Date: December 2, 2004 2:06:07 PM PST

Hey folks - question about the "human" exposure response in rpict (ximage) versus pcond. When I render an image (call it "output.hdr") and display it in ximage, I hit the "h" key and the image gets redisplayed with the "human" exposure mapping. Then i take output.hdr and i put it through

pcond -h output.hdr > output_cond.hdr

(now call the new conditioned file "output_cond.hdr") When i display "output_cond.hdr" in ximage, i get a different resulting image than when I viewed output.hdr in ximage and hit "h". The ximage "h" version of output.hdr is darker and has more contrast than the output_cond.hdr image. What's up with that?

thanks,

kirk

Cool - I will try pcond -c -s and see what happens.

Thanks,

kirk

···

On Dec 2, 2004, at 5:44 PM, Gregory J. Ward wrote:

Hi Kirk,

Ximage using the 'h' command or the -e human option is more-or-less equivalent to pcond -c -s, but the -h option of pcond turns on acuity and veiling glare filters (-v and -a) that are not included in ximage. The veiling glare in particular can reduce the image contrast, especially around bright sources and objects. Also, pcond using foveal-size (1 degree) luminance samples, rather than pixels, and this can result in a different tone curve.

-Greg (waving his hands wildly)

From: Kirk Thibault <[email protected]>
Date: December 2, 2004 2:06:07 PM PST

Hey folks - question about the "human" exposure response in rpict (ximage) versus pcond. When I render an image (call it "output.hdr") and display it in ximage, I hit the "h" key and the image gets redisplayed with the "human" exposure mapping. Then i take output.hdr and i put it through

pcond -h output.hdr > output_cond.hdr

(now call the new conditioned file "output_cond.hdr") When i display "output_cond.hdr" in ximage, i get a different resulting image than when I viewed output.hdr in ximage and hit "h". The ximage "h" version of output.hdr is darker and has more contrast than the output_cond.hdr image. What's up with that?

thanks,

kirk

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Take those waving hands and, hot diggitty dog, slap 'em together: -c -s was the ticket. That veiling glare will get you every time....

kirk

···

On Dec 2, 2004, at 5:44 PM, Gregory J. Ward wrote:

Hi Kirk,

Ximage using the 'h' command or the -e human option is more-or-less equivalent to pcond -c -s, but the -h option of pcond turns on acuity and veiling glare filters (-v and -a) that are not included in ximage. The veiling glare in particular can reduce the image contrast, especially around bright sources and objects. Also, pcond using foveal-size (1 degree) luminance samples, rather than pixels, and this can result in a different tone curve.

-Greg (waving his hands wildly)

From: Kirk Thibault <[email protected]>
Date: December 2, 2004 2:06:07 PM PST

Hey folks - question about the "human" exposure response in rpict (ximage) versus pcond. When I render an image (call it "output.hdr") and display it in ximage, I hit the "h" key and the image gets redisplayed with the "human" exposure mapping. Then i take output.hdr and i put it through

pcond -h output.hdr > output_cond.hdr

(now call the new conditioned file "output_cond.hdr") When i display "output_cond.hdr" in ximage, i get a different resulting image than when I viewed output.hdr in ximage and hit "h". The ximage "h" version of output.hdr is darker and has more contrast than the output_cond.hdr image. What's up with that?

thanks,

kirk

_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general