The MATLAB (Matrix Lab) Image processing Toolbox has a large variety of functions that supports a wide range of image processing operations, including:

• Geometric Operations

• Neighborhood and block operations

• Linear Filtering and filter design

• Transforms

• Image analysis and enhancement

• Binary image operations

• Region of interest operations

 MATLAB provides commands for reading, writing, and displaying several types of graphics file formats images. MATLAB supports the following graphics file formats.

• BMP  (Microsoft Windows Bitmap)

• HDF   (Hierarchical Data Format)

• JPEG  (Joint Photographic Experts Group)

• PCX   (Paintbrush)

• PNG   (Portable Network Graphics)

• TIFF  (Tagged Image File Format)

• XWD (X Window Dump)

 Texture Mapping                                                                                                                      

 Example                                                                                                                                   

[x,y,z]=cylinder;

i=imread('zia3.jpg');

imhow(i);

warp(x,y,z,i);   

 Result                                                                                                                                      

Following figure is after warp(x,y,z,i)

 Querying a Graphics file                                                                                                            

 Example                                                                                                                                   

imfinfo('zeya.bmp')

 Result                                                                                                                                      

ans =

Filename: 'zeya.bmp'
FileModDate: '26-Oct-2009 01:44:16'
FileSize: 213470
Format: 'bmp'
FormatVersion: 'Version 3 (Microsoft Windows 3.x)'
Width: 345
Height: 206
BitDepth: 24
ColorType: 'truecolor'
FormatSignature: 'BM'
NumColormapEntries: 0
Colormap: []
RedMask: []
GreenMask: []
BlueMask: []
ImageDataOffset: 54
BitmapHeaderSize: 40
NumPlanes: 1
CompressionType: 'none'
BitmapSize: 213416
HorzResolution: 0
VertResolution: 0
NumColorsUsed: 0
NumImportantColors: 0

 Adding a Colorbar                                                                                                                    

 Example                                                                                                                                   

i=imread('zia3.jpg');

imshow(i),colorbar

 Result                                                                                                                                      

 Storing  TIFF and PNG file formats                                                                                                                                                                                                                                            

 Task #1                                                                                                                                   

 How we can store TIFF and PNG file formats

 Solution                                                                                                                                    

    i = imread('zia2.tif');

     imshow (i);

     imwrite(i,'zeeya.bmp');

 Result                                                                                                                                       

Above file (zia2.tif) saved as zeeya.bmp

 Querying a Graphics file                                                                                                           

 Task # 2                                                                                                                                  

 What information is at least available for different file formats?

  Compare BMP, PNG, TIFF and JPG file formats descriptions via imfinfo

Result                                                                                                                                       

  Filename

  FileModDate

  FileSize

  Format

  FormatVersion

  Width

  Height

  BitDepth

  ColorType

  FormatSignature

Note: Above is maximum information available by JPG file format, all other formats include this information in excess.                         

 HELP                                                                                                                                       

 IMREAD                                                                                                                                  

 IMREAD Read image from graphics file.
A = IMREAD(FILENAME,FMT) reads the image in FILENAME into A. If the file contains a grayscale intensity image, A is a two-dimensional array. If the file contains a truecolor (RGB) image, A is a three-dimensional (M-by-N-by-3) array.
FILENAME is a string that specifies the name of the graphics file, and FMT is a string that specifies the
format of the file. The file must be in the current directory or in a directory on the MATLAB path. If IMREAD
cannot find a file named FILENAME, it looks for a file named FILENAME.FMT.

The possible values for FMT include:
'jpg' or 'jpeg' Joint Photographic Experts Group (JPEG)
'tif' or 'tiff' Tagged Image File Format (TIFF)
'bmp' Windows Bitmap (BMP)
'png' Portable Network Graphics
'hdf' Hierarchical Data Format (HDF)
'pcx' Windows Paintbrush (PCX)
'xwd' X Window Dump (XWD)

[X,MAP] = IMREAD(FILENAME,FMT) reads the indexed image in FILENAME into X and its associated colormap into MAP. Colormap values in the image file are automatically rescaled into the range [0,1].

[...] = IMREAD(FILENAME) attempts to infer the format of the file from its content.

Data types
In most of the image file formats supported by IMREAD, pixels are stored using 8 or fewer bits per color plane.
When reading such a file, the class of the output (A or X) is uint8. IMREAD also supports reading 16-bit-per-pixel data from TIFF and PNG files; for such image files, the class of the output (A or X) is uint16.

TIFF-specific syntaxes
[...] = IMREAD(...,IDX) reads in one image from a multi-image TIFF file. IDX is an integer value that
specifies the order that the image appears in the file. For example, if IDX is 3, IMREAD reads the third image in
the file. If you omit this argument, IMREAD reads the first image in the file.

PNG-specific syntaxes
[...] = IMREAD(...,'BackgroundColor',BG) composites any transparent pixels in the input image against the color specified in BG. If BG is 'none', then no compositing is performed. Otherwise, if the input image is indexed, BG should be an integer in the range [1,P] where P is the colormap length. If the input image is grayscale, BG should be an integer in the range [0,1]. If the input image is RGB, BG should be a three-element vector whose values are in the range [0,1]. The string 'BackgroundColor' may be abbreviated.

If the ALPHA output argument is used (see below), then BG defaults to 'none' if not specified by the
user. Otherwise, if the PNG file contains a background color chunk, that color is used as the default value for
BG. If ALPHA is not used and the file does not contain a background color chunk, then the default value for BG is 1 for indexed images; 0 for grayscale images; and [0 0 0] for RGB images.

[A,MAP,ALPHA] = IMREAD(...) returns the alpha channel if
one is present; otherwise ALPHA is []. Note that MAP may
be empty if the file contains a grayscale or truecolor
image.

HDF-specific syntaxes
[...] = IMREAD(...,REF) reads in one image from a multi-image HDF file. REF is an integer value that
specifies the reference number used to identify the image. For example, if REF is 12, IMREAD reads the image whose reference number is 12. (Note that in an HDF file the reference numbers do not necessarily correspond with the order of the images in the file. You can use IMFINFO to match up image order with reference number.) If you omit this argument, IMREAD reads the first image in the file.

Supported file types
JPEG Any baseline JPEG image; JPEG images with some commonly used extensions
TIFF Any baseline TIFF image, including 1-bit, 8-bit, and 24-bit uncompressed images; 1-bit, 8-bit, and 24-bit
images with packbits compression; 1-bit images with CCITT compression; also, 16-bit grayscale, 16-bit
indexed, and 48-bit RGB images
BMP 1-bit, 4-bit, 8-bit, and 24-bit uncompressed images; 4-bit and 8-bit run-length encoded (RLE) images
PNG Any PNG image, including 1-bit, 2-bit, 4-bit, 8-bit, and 16-bit grayscale images; 8-bit and 16-bit
indexed images; 24-bit and 48-bit RGB images
HDF 8-bit raster image datasets, with or without an associated colormap; 24-bit raster image datasets
PCX 1-bit, 8-bit, and 24-bit images
XWD 1-bit and 8-bit ZPixmaps; XYBitmaps; 1-bit XYPixmap

 IMSHOW                                                                                                                                

IMSHOW Display image.
IMSHOW(I,N) displays the intensity image I with N discrete levels of gray. If you omit N, IMSHOW uses 256 gray levels on 24-bit displays, or 64 gray levels on other systems.

IMSHOW(I,[LOW HIGH]) displays I as a grayscale intensity image, specifying the data range for I. The value LOW (and any value less than LOW) displays as black, the HIGH (and any value greater than HIGH) displays  as white, and values in between display as intermediate shades of gray. IMSHOW uses the default number of gray levels. If you use an empty matrix ([]) for [LOW HIGH], IMSHOW uses [min(I(:)) max(I(:))]; the minimum value in I displays as black, and the maximum value displays as white.
IMSHOW(BW) displays the binary image BW. Values of 0 display as black, and values of 1 display as white.
IMSHOW(X,MAP) displays the indexed image X with the colormap MAP.
IMSHOW(RGB) displays the truecolor image RGB.
IMSHOW(...,DISPLAY_OPTION) displays the image, calling
TRUESIZE if DISPLAY_OPTION is 'truesize', or suppressing the call to TRUESIZE if DISPLAY_OPTION is 'notruesize'. Either option string can be abbreviated. If you do not supply this argument, IMSHOW determines whether to call TRUESIZE based on the setting of the 'ImshowTruesize' preference.
IMSHOW(x,y,A,...) uses the 2-element vectors x and y to establish a nondefault spatial coordinate system, by
specifying the image XData and YData.

IMSHOW(FILENAME) displays the image stored in the graphics file FILENAME. IMSHOW calls IMREAD to read the image from the file, but the image data is not stored in the MATLAB workspace. The file must be in the current directory or on the MATLAB path.
H = IMSHOW(...) returns the handle to the image object created by IMSHOW.
 

Class Support
The input image can be of class uint8, uint16, or double.
 

Remarks
You can use the IPTSETPREF function to set several toolbox preferences that modify the behavior of IMSHOW:
- 'ImshowBorder' controls whether IMSHOW displays the image with a border around it.
- 'ImshowAxesVisible' controls whether IMSHOW displays the image with the axes box and tick labels.
- 'ImshowTruesize' controls whether IMSHOW calls the TRUESIZE function.
For more information about these preferences, see the reference entry for IPTSETPREF.

 IPTSETPREF                                                                                                                           

IPTSETPREF Set Image Processing Toolbox preference.
IPTSETPREF(PREFNAME,VALUE) sets the Image Processing Toolbox preference specified by the string PREFNAME to VALUE. The setting persists until the end of the current MATLAB session, or until you change the setting. (To make the value persist between sessions, put the command in your startup.m file.)
Preference names are case insensitive and can be abbreviated.

The following preference values can be set:
'ImshowBorder' 'loose' (default) or 'tight'
If 'ImshowBorder' is 'loose', IMSHOW displays images with a border between the image and the edges of the
figure window, thus leaving room for axes labels, titles, etc. If 'ImshowBorder' is 'tight', then IMSHOW
adjusts the figure size so that the image entirely fills the figure. (However, there may still be a border if the
image is very small, or if there are other objects besides the image and its axes in the figure.)
'ImshowAxesVisible' 'on' or 'off' (default)
If 'ImshowAxesVisible' is 'on', IMSHOW displays images with the axes box and tick labels. If
'ImShowAxesVisible' is 'off', IMSHOW displays images without the axes box and tick labels.
'ImshowTruesize' 'auto' (default) or 'manual'
If 'ImshowTruesize' is 'manual', IMSHOW does not call TRUESIZE. If 'ImshowTruesize' is 'auto', IMSHOW
automatically decides whether to call TRUESIZE. (IMSHOW calls TRUESIZE if there will be no other objects in the resulting figure besides the image and it axes.) You can override this setting for an individual display by
specifying the DISPLAY_OPTION argument to IMSHOW, or you can call TRUESIZE manually after displaying the image.
'TruesizeWarning' 'on' (default) or 'off'
If 'TruesizeWarning' is 'on', TRUESIZE displays a warning if the image is too large to fit on the
screen. If 'TruesizeWarning' is 'off', TRUESIZE does not display the warning. Note that this preference applies
even when you call TRUESIZE indirectly, such as through IMSHOW.
IPTSETPREF(PREFNAME) displays the valid values for PREFNAME.

Example
iptsetpref('ImshowBorder', 'tight')

 IMFINFO                                                                                                                                

IMFINFO Information about graphics file.
INFO = IMFINFO(FILENAME,FMT) returns a structure whose fields contain information about an image in a graphics file. FILENAME is a string that specifies the name of the graphics file, and FMT is a string that specifies the format of the file. The file must be in the current directory or in a directory on the MATLAB path. If IMFINFO cannot find a file named FILENAME, it looks for a file named FILENAME.FMT.
The possible values for FMT include:
 

'bmp' Windows Bitmap (BMP)
'hdf' Hierarchical Data Format (HDF)
'jpg' or 'jpeg' Joint Photographric Experts Group
'pcx' Windows Paintbrush (PCX)
'png' Portable Network Graphics (PNG)
'tif' or 'tiff' Tagged Image File Format (TIFF)
'xwd' X Window Dump (XWD)

If FILENAME is a TIFF or HDF file containing more than one image, INFO is a structure array with one element for each image in the file. For example, INFO(3) would contain information about the third image in the file.
INFO = IMFINFO(FILENAME) attempts to infer the format of the file from its content.

The set of fields in INFO depends on the individual file and its format. However, the first nine fields are always the same. These common fields are:

Filename A string containing the name of the file; if the file is not in the current directory, the
string contains the full pathname of the file

FileModDate A string containing the modification date of the file

FileSize An integer indicating the size of the file in bytes

Format A string containing the file format, as specified by FMT; for JPEG and TIFF files, the three-letter variant is returned

FormatVersion A string or number specifying the file format version

Width An integer indicating the width of the image in pixels

Height An integer indicating the height of the image in pixels

BitDepth An integer indicating the number of bits per pixel

ColorType A string indicating the type of image; either 'truecolor' for a truecolor (RGB) image, 'grayscale' for a grayscale intensity image, or 'indexed', for an indexed image

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