HDRI LED capture interesting artifacts

Hello!

I've got some interesting artifacts on my images of a single LED, and I'm
curious how to interpret and overcome them.

Please see two images at:

The settings for taking both are the following:

*1 ND filter output7.jpg*

Range of shutter speed 1/8000 to 1/15’’ with aperture f16

Range 1/30’’ to 15’’ with aperture f4

Luminance of reflectance standards:

99% 197.2 cd/m^2

40% 99.3 cd/m^2

ND filter t =0.0094

···

*
2 ND filters output14.jpg*

Range 1/8000 to 1/15’’ with aperture f16

Range 1/30’’ to 15’’ with aperture f4

Ambient light level (illuminance meter) E=667 lx

Luminance of reflectance standards:

99% 215 cd/m^2

40% 106.3 cd/m^2

ND filter t =0.0094

2nd ND filter t2=0.4375

Thank you,
Yulia

Hi Yulia,

There is an occasional issue with dcraw where it doesn't quite handle the highlights correctly, leaving this pink area near the brightest part of the exposure. The only fix I've found is to set the -b option to a larger value. You should try this with raw2hdr. Try "raw2hdr -b 1.3 ..." adding your other options as usual. If that doesn't get rid of the pink haloes, keep increasing the value until it does.

If this doesn't work, then maybe you need more exposures. I'm not really sure unless I can play with your original RAW files what else it could be.

Best,
-Greg

···

From: "Tyukhova, Yulia" <[email protected]>
Date: February 23, 2012 9:10:13 AM PST

Hello!

I've got some interesting artifacts on my images of a single LED, and I'm curious how to interpret and overcome them.

Please see two images at:
http://www.mediafire.com/?6w6tfmpoqtpipap,c0e69acf1x51ndu

The settings for taking both are the following:
1 ND filter output7.jpg
Range of shutter speed 1/8000 to 1/15’’ with aperture f16
Range 1/30’’ to 15’’ with aperture f4
Luminance of reflectance standards:
99% 197.2 cd/m^2
40% 99.3 cd/m^2
ND filter t =0.0094

2 ND filters output14.jpg
Range 1/8000 to 1/15’’ with aperture f16
Range 1/30’’ to 15’’ with aperture f4
Ambient light level (illuminance meter) E=667 lx
Luminance of reflectance standards:
99% 215 cd/m^2
40% 106.3 cd/m^2
ND filter t =0.0094
2nd ND filter t2=0.4375

Thank you,
Yulia