$($Java code$)$ PPM stands for Aortable Pixmap. Ifs a simple file format that can be used to save and retrieve digital image data from files and to transfer them between machines and operating systems. Unlike JPG$.$ PNG$,$ and GIF formats, PPM does not use any compression $/$decompression schemes maling reading and writing PPM flies relatuely easier. For this assignment, we will simplify the PPM format further, dealing only with the essentials. For more details about PPM$,$ refer to the Wikipedia entry

$1$ Decoding PPM data

The contents of a sample PPM file is shown in the following box. It encodes information about a small imageThe PPM file is divided into two sections. a header section $($the first three lines$)$ and a data section $($everything that follows the header$).$ The frst line of a PPM fie always contains the characters P$3.$ This is called the file's magic number and is used to distinguish files of different types. If the first line does not contain the characters P$3,$ then we know it's not a PPM fileUne $2$ contains two numbers which are the width and height of the image $($in that order$).$ In the example above, the image is $3$ pixels wide and $2$ pixels high.

Line $3$ contains the number $255$ which is called the color depth, which is the maximum value for the red, green, and blue components of a pixel color

Lines $4$ and $5$ are the data section of this PPIM file. Since this image is $3$ pixels wide and $2$ pixels high the total number of poxels is $6.$ And since each pixel is saved as three integers $($RGB triplet$),$ there is a total of $18$ integers in the data section. In the example above, the first row contains three pixels that have colors red $(255,0,0),$ green $(0,255,0),$ and blue $(0,0,255).$ The second row has yellow $(255,255,0).$ white $(255\mathrm{.}255\mathrm{.}255),$ and black $(0,0,0)$ pixels

To decode a PPM file, we follow these steps in sequence:

Read a line from the file and make sure it says P$3$

Read an integer from the file $($call it $w,$ the width$).$

Read another integer from the file $($call it h$,$ the height$)$

Read another integer from the file $($call it $d,$ the color depth$)$

Create a canvas with the given width and height.

For each row $1($from $0$ to $h-1)$

For each columnj $($from $01$o w$-1)$

Read an integer $r.$

Read an integer $9$

Read an integer $b$

Set the pixel color at coordinates $(0\mathrm{.}9)10(\frac{255.}{d},\frac{255.g}{d},\frac{255\mathrm{.}5}{d})$

$2$ Encoding PPM Data

Encoding is the process of saving an image data to a PPM file. To do this, we follow these steps in sequence:

Open the file for writing.

Write P$3$ on a line.

Write the image's width and height on the following line.

Write the number $255$ on the following line.

For each row i $($from $0$ to $h-1)$:

For each columnj $($from $0$ to $w-1)$

Gel the pixel at coordinates $(0\mathrm{.}1)$ of the image

Wirite the red, green, and blue numbers, separated by spaces

If we're at the last column in the row, print a newline character. Otherwise, print a space.

Flush the file's output.

$3$ Interface and Implementation of Codecs

The following is the interface for ImageCodec $($coder$/$decoder$)$The method decode takes an input stream containing image data, and retums a mutable image containing the decoded image. The method encode takes an image and an output strearn and prints the image data into the output stream. The method load is like decode except that it takes a fie name from witich the data $1$s toaded. The method sove, similarty, saves the image data to a flleWrite the class PPMCodec that implements imageCodec. It must encode and decode the streams according to the specifications listed in this assignment.