Image to numeric array

[Dimitrios Charitatos]

Hello,

I suspect that there is a quite straight forward answer to this, but I can't
find it... I want to import an image and extract a matrix (or array) from it
with elements showing the RGB value of each pixel. But I want to be able to do
this with all types of image formats. It was suggested that a function such as
'B = numeric.from_image(A)' was used but I can't find it in any of the
libraries. I was hoping you could help me on this.

Thank you,
Dimitris

[Diez B. Roggisch]

Dimitrios Charitatos wrote:

Hello,

I suspect that there is a quite straight forward answer to this, but I
can't find it... I want to import an image and extract a matrix (or array)
from it with elements showing the RGB value of each pixel. But I want to
be able to do this with all types of image formats. It was suggested that
a function such as 'B = numeric.from_image(A)' was used but I can't find
it in any of the libraries. I was hoping you could help me on this.

You have to install the numeric library for that. Googling numeric python
will bring you there pretty quick.

Diez

[Claudio Grondi]

Diez B. Roggisch wrote:

Dimitrios Charitatos wrote:

Hello,

I suspect that there is a quite straight forward answer to this, but I
can't find it... I want to import an image and extract a matrix (or array)
from it with elements showing the RGB value of each pixel. But I want to
be able to do this with all types of image formats. It was suggested that
a function such as 'B = numeric.from_image(A)' was used but I can't find
it in any of the libraries. I was hoping you could help me on this.

You have to install the numeric library for that. Googling numeric python
will bring you there pretty quick.

Diez

Is there a difference between the 'Numeric' and 'numeric' module?
I have on my system only Numeric... And this has no function like
'from_image'.

The usual way of doing such things is to use PIL (Python Image Library)
to load the image from file, then export it from PIL to a Python string
in order to import from this string to an array of the targeted
numerical module.

Really curious if there is a direct way in any of the numerical
packages, as it would save the time and effort of unnecessary
conversions from PIL, ImageMagick or from other image libraries.

Claudio

[Diez B. Roggisch]

> Is there a difference between the 'Numeric' and 'numeric' module?

I have on my system only Numeric... And this has no function like
'from_image'.
I actually didn't check that - I just wanted to point the OP to the
numeric-module(s) available, as he suggested that
The usual way of doing such things is to use PIL (Python Image Library)
to load the image from file, then export it from PIL to a Python string
in order to import from this string to an array of the targeted
numerical module.
I'd go for the getdata() method instead.
Really curious if there is a direct way in any of the numerical
packages, as it would save the time and effort of unnecessary
conversions from PIL, ImageMagick or from other image libraries.

Whatever module is capable of converting needs to know how to read images -
either by itself, or by means of another module.
I know for sure that pygame supports retrieving pixel-data as array.

Diez

[Claudio Grondi]

Diez B. Roggisch wrote:

Is there a difference between the 'Numeric' and 'numeric' module?
I have on my system only Numeric... And this has no function like
'from_image'.

I actually didn't check that - I just wanted to point the OP to the
numeric-module(s) available, as he suggested that

The usual way of doing such things is to use PIL (Python Image Library)
to load the image from file, then export it from PIL to a Python string
in order to import from this string to an array of the targeted
numerical module.

I'd go for the getdata() method instead.

Yes, you are right.
Sorry, I should have checked it in source code before posting just from
my memory. Usage of .tostring() was my first approach - I have replaced
it later by .getdata() because of speed issues (we are speaking here
about methods of the Image module available after installation of PIL).
As I have experience with numarray only, I can't help here directly with
a code example for Numeric.

Claudio

Really curious if there is a direct way in any of the numerical
packages, as it would save the time and effort of unnecessary
conversions from PIL, ImageMagick or from other image libraries.

Whatever module is capable of converting needs to know how to read images -
either by itself, or by means of another module.
I know for sure that pygame supports retrieving pixel-data as array.

Diez