Interpolation methods                                                                                                                                                                                                                                                                   

 Task 1                                                                                                                                      

 Describe above interpolation methods.

 Solution                                                                                                                                    

im = imread('flowers.tif');

imshow(im)

im1 = im(:,:,1);

figure, imshow(im1)

im2 = im(:,:,2);

figure, imshow(im2)

im3 = im(:,:,3);

figure, imshow(im3)

g = rgb2gray(im);

figure, imshow(g)

h = g > 73;

figure, imshow(h)

hn = ~h;

figure, imshow(hn)

bwl = bwlabel(hn);

figure, imshow(bwl)

imagesc(bwl), colormap(gray), axis image

ob3 = bwl ==63

pixval on

figure, imshow(ob3)

 Result                                                                                                                                       

Note:

1)  im1 = im(:,:,1),  im2 =im (:,:,2) and  im3 =im (:,:,3) separated out red, green and blue components of image.

2) g = rgb2gray(im) converted the RGB image to gray scale image, which when threshold on 73 gives us binary image.

3) The hn = ~h  command negated the binary image that is white to black and black to whitel

4) The bwl = bwlabel(hn) command enabled a pixel location display when the mouse moved on the image.

5) The ob3 = bwl == 63  command only showed the portion of the binary image where the pixel value equals      to    63.

 HELP                                                                                                                                       

 BWLABEL                                                                                                                                

 BWLABEL Label connected components in binary image.
L = BWLABEL(BW,N) returns a matrix L, of the same size as BW, containing labels for the connected components in BW. N can have a value of either 4 or 8, where 4 specifies 4-connected objects and 8 specifies 8-connected objects; if the argument is omitted, it defaults to 8.
The elements of L are integer values greater than or equal to 0. The pixels labeled 0 are the background. The pixels labeled 1 make up one object, the pixels labeled 2 make up a second object, and so on.
[L,NUM] = BWLABEL(BW,N) returns in NUM the number of connected objects found in BW.

Class Support
The input image BW can be of class double or uint8. The output matrix L is of class double.

Example
 

BW = [1 1 1 0 0 0 0 0
             1 1 1 0 1 1 0 0
             1 1 1 0 1 1 0 0
             1 1 1 0 0 0 1 0
             1 1 1 0 0 0 1 0
             1 1 1 0 0 0 1 0
             1 1 1 0 0 1 1 0
             1 1 1 0 0 0 0 0];
 L = bwlabel(BW,4);
[r,c] = find(L == 2);

 RGB2GRAY                                                                                                                             

RGB2GRAY Convert RGB image or colormap to grayscale.
RGB2GRAY converts RGB images to grayscale by eliminating the hue and saturation information while retaining the luminance.
I = RGB2GRAY(RGB) converts the truecolor image RGB to the grayscale intensity image I.
NEWMAP = RGB2GRAY(MAP) returns a grayscale colormap equivalent to MAP.

Class Support
If the input is an RGB image, it can be of class uint8, uint16 or double; the output image I is of the same class as the input image. If the input is a colormap, the input  and output colormaps are both of class double.

 COLORMAP                                                                                                                           

COLORMAP Color look-up table.
COLORMAP(MAP) sets the current figure's colormap to MAP. COLORMAP('default') sets the current figure's colormap to the root's default, whose setting is JET.
MAP = COLORMAP retrieves the current colormap. The values are in the range from 0 to 1.
A color map matrix may have any number of rows, but it must have exactly 3 columns. Each row is interpreted as a color, with the first element specifying the intensity of red light, the second  green, and the third blue. Color intensity can be specified on the interval 0.0 to 1.0.
For example, [0 0 0] is black, [1 1 1] is white,  [1 0 0] is pure red, [.5 .5 .5] is gray, and [127/255 1 212/255] is aquamarine.
Graphics objects that use pseudocolor -- SURFACE and PATCH objects, which are created by the functions MESH, SURF, and PCOLOR -- map a color matrix, C, whose values are in the range [Cmin, Cmax], to an array of indices, k, in the range [1, m]. The values of Cmin and Cmax are either min(min(C)) and max(max(C)), or are specified by CAXIS. The mapping is linear, with Cmin mapping to index 1 and Cmax mapping to index m. The indices are then used with the colormap to determine the color associated with each matrix element. See CAXIS for details.
Type HELP GRAPH3D to see a number of useful colormaps.
COLORMAP is an M-file that sets the Colormap property of the current figure.               

 IMAGESC                                                                                                                                

IMAGESC Scale data and display as image.
IMAGESC(...) is the same as IMAGE(...) except the data is scaled to use the full colormap.
IMAGESC(...,CLIM) where CLIM = [CLOW CHIGH] can specify the scaling.

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