Synth-DIY Yahoo! Groups Archives

Linear Grayscale crash in Spyder2PRO

2007-08-31 by marko.mili

When trying to use "Linear Grayscale" for gamma, Spyder2PRO
crashes after doing the calibration, as it tries to create the
profile. This is on Intel Mac, latest version downloaded from the website.

Is anyone else having this problem?

In addition, does anyone know what this option tries to achieve? I
assume it shapes the gamma curve such that luminosity of grayscale
wedges appears linear, to match linearized printing setups like QTR
and such? I was unable to find an adequate description in the helpfile
or by googling for it. Is this similar in intent to L* gamma curve in
ColorEyes?

Thanks,
Marko

Re: [colorvision_group] Linear Grayscale crash in Spyder2PRO

2007-09-01 by CDTobie@aol.com

In a message dated 8/31/07 5:49:22 PM, marko.mili@... writes:

When trying to use "Linear Grayscale" for gamma, Spyder2PRO
crashes after doing the calibration, as it tries to create the
profile. This is on Intel Mac, latest version downloaded from the website.

Is anyone else having this problem?

Haven't seen it, or heard of it from anyone else... I'll try to replicate it, but its really not a choice that you'll want to be using, so it won't matter for your uses.

In addition, does anyone know what this option tries to achieve?

It achieves a linear grayscale (gamma 1.0) for certain scientific uses.

I
assume it shapes the gamma curve such that luminosity of grayscale
wedges appears linear, to match linearized printing setups like QTR
and such? I was unable to find an adequate description in the helpfile
or by googling for it. Is this similar in intent to L* gamma curve in
ColorEyes?

No, we'll be offering L-Star calibration options in future products, but in Spyder2PRO you'd have to load the L-Star calibration curve yourself to calibrate to L-Star. L-Star is roughly gamma 2.2, so its far away from linear, gamma 1.0.

Gamma 2.2 and L-Star are both aimed, in a general sense, at reproducing the human response to light, that is what seems to be consistant units to the eye. Linear, gamma 1.0, response is mathematically linear, not linear to the eye. RAW image files, for instance, are linear. They are basically unviewable until converted to gamma 2.2, L-Star or some other curve that emulates the human eye's tonal response.

C. David Tobie
Product Technology Manager
ColorVision Business Division
DataColor Inc.
CDTobie@...
www.colorvision.com

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Linear Grayscale crash in Spyder2PRO

Linear Grayscale crash in Spyder2PRO

Re: [colorvision_group] Linear Grayscale crash in Spyder2PRO

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