Cycles Gradient Texture node: Why "Linear" is not linear on a "default" plane? I want to render a plane with a linear gradient texture that can be rotated as needed.

I've set up a basic working node network as shown:


I can rotate the gradient using the Mapping Node - > Texture -> Rotation.Z coordinate, however the rendered gradient is always logarithmic rather than linear:  



This is the true linear gradient that I am looking for:



I've played around with the scale and location vectors but they have no impact on the linearity of the gradient.

Here's my scene (1 plane, 1 sun lamp, orthographic camera):



A similar question was asked a while ago over here but no real answer was given.

Any suggestions would be appreciated.



[Update]

It seems this may be due to the Color Management applied by Cycles.  I'm using Cycles because as I believe you can't rotate gradients (blends) in BI.  If this is not right, please let me know.

I'm really just trying to determine if it is possible in Blender to render 2D shadow mask planes using true linear gradients. I alrteady have 3D geometry that the masks need to fit perfectly against, so I extruded edges from these objects to create new 2D planes.
[End Update]
I think that the gradient is linear in its values because at equal increments of the thereshold correspond the same amount of image masking:



As stated by the Blender reference manual's page about Color Management,  Default option does no extra conversion..


  ..besides the conversion for the display device


So a converision still occurs.

By switching to Raw you'll get a result almost identical to the one expected. Again from the same manual page:


  Raw gives the image without any color space conversion




On the right you can see a linear gradient image for comparison.



Object coordinates are calculated from object's origin.

.

If you want a gradient that starts from the bottom of the plane, you should move the origin of the object's texture coordinates (so the Object's  origin) at the bottom of the plane too (the default plane's origin is instead located in its center).