Thread Subject:

getting the data points from an image

I have a set of data points (x and y vectors) which I plot
and then save as in image (jpg format). After processing
the image I get the coordinates of two pixels. I want to
find the data points (the x and y values) that represent
those "interesting" pixels so that I can analyze the data
used for the original plot.
Does any one have any suggestions?

Thanks
Yael

On Dec 10, 5:15 pm, "yael frankel" <y...@nospam.com> wrote:
> I have a set of data points (x and y vectors) which I plot
> and then save as in image (jpg format). After processing
> the image I get the coordinates of two pixels. I want to
> find the data points (the x and y values) that represent
> those "interesting" pixels so that I can analyze the data
> used for the original plot.
> Does any one have any suggestions?
>
> Thanks
> Yael

===================================
I totally don't understand. First you say that you "get the
coordinates of the two pixels." OK, to me that means that you have
now found the x and y values of the two pixels - that's pretty much
the definition of coordinates isn't it? OK, so now you have an (x1,
y1) pair and a (x2, y2) pair. Then you say "I want to find the data
points (the x and y values) that represent those "interesting"
pixels..." Huh? What do you mean find the x and y values? You said
in the first sentence that you had found them already!
Regards,
ImageAnalyst

It is very simple. Suppose your image data is stored in a variable Im. You know the co-ordinates, x and y then you can the value of the image as
>>Im(x,y)

A clarification.
What we have is: vectors of (x,y) locations - our data.
We can plot the data points and get a line.
What we need is: a matrix say 1000x1000 of 0,1, where line
= 1, background = 0.

We were thinking of going into a jpg and then back, but
found it difficult to relate the pixels to the original
axes values.

Is there a way to directly convert a plotted line to a
matrix?

Thanks
Daphne & Yael



"yael frankel" <y..@nospam.com> wrote in message
<fjkdqq$l7h$1@fred.mathworks.com>...
> I have a set of data points (x and y vectors) which I
plot
> and then save as in image (jpg format). After processing
> the image I get the coordinates of two pixels. I want to
> find the data points (the x and y values) that represent
> those "interesting" pixels so that I can analyze the
data
> used for the original plot.
> Does any one have any suggestions?
>
> Thanks
> Yael
>