How do RGB values converts to Numbers in the Image Sampler ?

Hi guys,

The direct output of the Image Sampler are RGB values, how do the three values get converted into one number when pluging the output into a number component ? Could that be a greyscale value ?

It'd be great if the image sampler could have an input and output on which one could hover and see the information similarly to other GH components.

cheers,

Arthur

Replies to This Discussion

Permalink Reply by David Rutten on October 15, 2010 at 9:14am

Hi Arthur,

double-click the image sampler to switch from colour sampling to other modes:

The last one in that list is the brightness sampling.

--
David Rutten
david@mcneel.com
Poprad, Slovakia

Permalink Reply by Arthur Mamou-Mani on October 18, 2010 at 10:36am

Thanks a lot David.
Anyone would know what the "interpolate" does by any chance ?
cheers

Permalink Reply by David Rutten on October 18, 2010 at 11:55am

Without interpolate, the sampler only looks at the pixel directly underneath the sampling coordinate. With interpolate on, it will also take neighbouring pixels into account when you're sampling 'in between' pixels.

--
David Rutten
david@mcneel.com
Poprad, Slovakia

Permalink Reply by Arthur Mamou-Mani on October 20, 2010 at 3:11am

Thanks David !

Sorry for being a bit demanding, do you think there could be a contrast slider in the image sampler or even as a separate component ? Contrast is the main thing I have been changing in photoshop to get better results it d be fantastic if it was directly into GH (my colleagues agree).

thanks again,

Arthur

Permalink Reply by Ola Jaensson on October 20, 2010 at 8:25am

Try to connect the image sampler (brightness) output to a graph mapper and try different graph types, beginning with the linear.

___________
Ola Jaensson

Permalink Reply by David Rutten on October 20, 2010 at 9:07am

Hi Arthur,

I can add all manner of pixel post-processing effects to the image sampler, I've already coded them up in Grasshopper. But wouldn't it make more sense to add contrast to your values after you get them out of the sampler?

--
David Rutten
david@mcneel.com
Poprad, Slovakia

Permalink Reply by Arthur Mamou-Mani on October 20, 2010 at 9:23am

Hi David,

I guess the good thing about putting it in the image sampler is being able to visualize the modifications on the image but as Ola mentionned, putting a parabolic graph after the sampler will probably do the job :)

Permalink Reply by David Rutten on October 20, 2010 at 2:52pm

Ok, I have about 20* or so pixel filters coded up for GUI purposes, but there's no reason why wouldn't work on large images as well. I'll need to figure out a good way to provide a UI for this though.

--
David Rutten
david@mcneel.com
Poprad, Slovakia

* though probably only about 10 or so useful ones for this purpose.

Permalink Reply by Joey Doherty on July 22, 2019 at 4:00pm

Hi David,

When Arthur plugged the image sampler into the number component the rgb value was converted into a single number. What is the conversion equation used to obtain these values?

Thank you

Joey Doherty

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