getPixelValue

Get pixel value as numeric array

Syntax

pixval = getPixelValue(imgmodel,r,c)

Description

pixval = getPixelValue(imgmodel,r,c) returns the numeric value of one or more pixels with (row, column) coordinate (r, c) in image model imgmodel.

Examples

Get RGB Pixel Values from Image Model

Pixel values obtained from an imagemodel object can be returned in several formats suitable for display in different interactive image processing tools.

Create an image model associated with a color image.

h = imshow('flamingos.jpg');

im = imagemodel(h)

 
im =
 
IMAGEMODEL object accessing an image with these properties:

       ClassType: 'uint8'
    DisplayRange: []
     ImageHeight: 972
       ImageType: 'truecolor'
      ImageWidth: 1296
    MinIntensity: []
    MaxIntensity: []

 

Select a pixel by specifying row and column coordinates. This pixel has (row, column) coordinates (100, 200).

r = 100;
c = 200;

Get the numeric value of the pixel using the getPixelValue function.

pxValue = getPixelValue(im,r,c)

pxValue = 1×3 uint8 row vector

   104    95    54

Get the default pixel information string using the getDefaultPixelInfoString function. This string depends on the type of image but does not use the pixel values. The pixel information string is suitable for use with the Pixel Information tool.

defaultPxInfoStr = getDefaultPixelInfoString(im)

defaultPxInfoStr = 
'[R G B]'

Using the same string format, get the pixel information string for the specified pixel by using the getPixelInfoString function.

pxInfoStr = getPixelInfoString(im,r,c)

pxInfoStr = 
'[104 95 54]'

Get the default pixel region string using the getDefaultPixelRegionString function. This string depends on the type of image but does not use the pixel values. The pixel region string is suitable for use with the Pixel Region tool.

defaultPxRegStr = getDefaultPixelRegionString(im)

defaultPxRegStr = 
    'R:000
     G:000
     B:000'

There are two steps to get the pixel region string for the specified pixel in the same string format. First, get a function formatFcn that formats numeric pixel values by using the getPixelRegionFormatFcn function. Then, specify the row and column coordinate of the pixel as input arguments to formatFcn to get the formatted string.

formatFcn = getPixelRegionFormatFcn(im);
pxRegStr = formatFcn(r,c)

pxRegStr = 1×1 cell array
    {'R:104↵G: 95↵B: 54'}

Input Arguments

imgmodel — Image model

scalar imagemodel object

Image model, specified as a scalar imagemodel object.

r — Row coordinate

positive integer | vector of positive integers

Row coordinate of pixel, specified as a positive integer or vector of positive integers.

c — Column coordinate

positive integer | vector of positive integers

Column coordinate of pixel, specified as a positive integer or vector of positive integers.

Output Arguments

pixval — Pixel value

numeric array | logical array

Pixel value, returned as one of the following.

Input Type	Return Format
p grayscale pixels	p-element numeric row vector
p RGB pixels	Numeric row vector of length p*3. The first p elements are the red value for each pixel. The next p elements are the green value for each pixel. The last p elements are the blue value for each pixel.
p binary pixels	p-element logical row vector
p indexed pixels	p-by-3 numeric array. Each row specifies a pixel. The columns specify the red, green, and blue components of the pixel value.

Version History

Introduced before R2006a