Colour Area percentage

[Satanic Mechanic]

Ok folks I once again must come to you again for advice and guidance. I have been through the searchs and can't quite see anything that is exactly what I am after but feel free to correct me on that. So here is the problem:

1. I have to work out the percentage areas of a certain colour randomly spread in patches over a photograph in this case usually brown - so far so good

2. So what I would like to do is this

a) Point to an example of the colour on the photograph and for other instances of this colour to be highlighted on the photo.
b) I then want to to adjust the 'range' of this colour (apologies for terminology) to include darker and lighter variations again for this to be highlighted on the photo

The above is similar in many ways to the 'Select by Colour' tool in Gimp

c) when I am happy with the 'range' - the area I have highlighted to be shown as a percentage.

I imagine this is not an uncommon process, but I just can seem to nail it or find the correct plug in.

[Michael Schmid]

Hi anonymous,

there are two pieces of software that I am aware of for selecting the
color range, but they won't directly give the percentage:
- Color Threshold, where you have to set the color range with sliders
- The Versatile Wand, where you can click to set the initial color; use
preview and non-contiguous mode.

  http://imagejdocu.tudor.lu/doku.php?id=plugin:segmentation:versatile_wand:start

(if the mailer splits it, the link should be one line).
You can then use 'measure' with 'area' activated in the measurement
options to get the area selected; a simple macro should be enough to
convert it to a fraction.
Alternatively, if you know a bit of java, you can add a message to the
Versatile Wand dialog, giving the percentage.

Michael
_________________________________________________________________________

On Sun, September 26, 2010 09:02, Satanic Mechanic wrote:

> Ok folks I once again must come to you again for advice and guidance. I
> have
> been through the searchs and can't quite see anything that is exactly what
> I
> am after but feel free to correct me on that. So here is the problem:
>
> 1. I have to work out the percentage areas of a certain colour randomly
> spread in patches over a photograph in this case usually brown - so far so
> good
>
> 2. So what I would like to do is this
>
> a) Point to an example of the colour on the photograph and for other
> instances of this colour to be highlighted on the photo.
> b) I then want to to adjust the 'range' of this colour (apologies for
> terminology) to include darker and lighter variations again for this to be
> highlighted on the photo
>
> The above is similar in many ways to the 'Select by Colour' tool in Gimp
>
> c) when I am happy with the 'range' - the area I have highlighted to be
> shown as a percentage.
>
> I imagine this is not an uncommon process, but I just can seem to nail it
> or
> find the correct plug in.
>

[Satanic Mechanic]

Michael

Many thanks for that - definitely along the right lines, just needs some refinement.

The wand outlines the areas fine but I really need is for it to 'fill in' the areas it has outlined and then tell me the percentage area of the shaded area to the whole picture.


I am desperately trying to learn programming (I even bought the book)but as I said in my previous thread I am more of a machinery person so it is not coming that naturally to me. If any one out there can assist me it would be great or at least give me some pointers.

Cheers folks

[Michael Schmid]

Hi anonymous,

as I wrote in my previous mail, if you have the selection from the  
wand, use 'Measure' with 'Area' selected in the Measurement options.  
It will give you the size of the selection.

Michael
________________________________________________________________

On 28 Sep 2010, at 03:00, Satanic Mechanic wrote:

> Michael
>
> Many thanks for that - definitely along the right lines, just needs  
> some
> refinement.
>
> The wand outlines the areas fine but I really need is for it to  
> 'fill in'
> the areas it has outlined and then tell me the percentage area of  
> the shaded
> area to the whole picture.
>
>
> I am desperately trying to learn programming (I even bought the  
> book)but as
> I said in my previous thread I am more of a machinery person so it  
> is not
> coming that naturally to me. If any one out there can assist me it  
> would be
> great or at least give me some pointers.
>
> Cheers folks