The PowerShell Guy

More fun with Bitmaps in Powershell ( PoSH Challenge part 10 )

As I entered another level about bitmaps, I will reflect a bit more about the way of working with bitmaps in PowerShell instead of posting the solution only. ( if this info is to much of a spoiler for this level you cheated some levels anyway ;-) )

The level was called odd even and involved a distorted bitmap ( paste in solution from Posh Challenge Part 9 into console for the bitmap )

So as in Level 7 ( PoSH Challenge part 6 ) and level 9 ( PoSH Challenge part 8 )  I started by loading the drawing namespace as it is not loaded by default ( actually I have it in my profile already, but for the example I ignored this  )

And loaded the bitmap into a variable ( $cave in this case) , and I also made a new empty bitmap,in this case half the size of the original (See Title of level) for the result, you can see in the session below I got this information by looking at the contents of the $cave variable.

PoSH> [System.Reflection.Assembly]::LoadWithPartialName("System.Drawing")                                               
                                                                                                                        
GAC    Version        Location                                                                                          
---    -------        --------                                                                                          
True   v2.0.50727     C:\WINDOWS\assembly\GAC_MSIL\System.Drawing\2.0.0.0__b03f5f7f11d50a3a\System.Drawing.dll          
                                                                                                                        
                                                                                                                        
PoSH> $Cave = [System.Drawing.Bitmap]::FromFile( 'C:\PowerShell\PoshChallenge\cave.jpg' )                               
PoSH> $cave                                                                                                             
                                                                                                                        
                                                                                                                        
Tag                  :                                                                                                  
PhysicalDimension    : {Width=640, Height=480}                                                                          
Size                 : {Width=640, Height=480}                                                                          
Width                : 640                                                                                              
Height               : 480                                                                                              
HorizontalResolution : 72                                                                                               
VerticalResolution   : 72                                                                                               
Flags                : 77960                                                                                            
RawFormat            : [ImageFormat: b96b3cae-0728-11d3-9d7b-0000f81ef32e]                                              
PixelFormat          : Format24bppRgb                                                                                   
Palette              : System.Drawing.Imaging.ColorPalette                                                              
FrameDimensionsList  : {7462dc86-6180-4c7e-8e3f-ee7333a7a483}                                                           
PropertyIdList       : {20624, 20625}                                                                                   
PropertyItems        : {20624, 20625}                                                                                   
                                                                                                                        
                                                                                                                        
                                                                                                                        
PoSH> $Cave2 = New-Object System.Drawing.Bitmap(320 , 240)                                                              
PoSH>                                                                                   

To select only the even pixels I use a double for loop for the $x and $y , I use two extra counter here $i and $j , I could also have have divided the X and Y by 2 but this was handier as I had to do some testing before I got to the final answer.

$i = 0

for ($x = 0;$x -lt 640;$x+=2) {
    $j = 0
    for ($y = 0;$y -lt 480;$y+=2) {
        $Cave2.SetPixel($i,$j,$Cave.GetPixel($x,$y))
        $j ++
    }
    $i ++
}

In this loop the only thing I do is copying the even pixels to the new bitmap

And what was left is saving the new bitmap and using the invoke-Item (ii) cmdlet to launce the default viewer to look at the results :

$Cave2.Save("C:\PowerShell\PoshChallenge\CAVE2.jpg")
ii CAVE2.jpg

Making the complete solution for Level 10 :

[System.Reflection.Assembly]::LoadWithPartialName("System.Drawing")

$Cave = [System.Drawing.Bitmap]::FromFile( 'C:\PowerShell\PoshChallenge\cave.jpg' )
$Cave2 = New-Object System.Drawing.Bitmap(320 , 240)

$i = 0
for ($x = 0;$x -lt 640;$x+=2) {
  $j = 0
  for ($y = 0;$y -lt 480;$y+=2) {
    $Cave2.SetPixel($i,$j,$Cave.GetPixel($x,$y))
    $j ++
  }
  $i ++
}

$Cave2.Save("C:\PowerShell\PoshChallenge\CAVE2.jpg")
ii CAVE2.jpg

In the next level more bitmaps, but then not bitmaps yet ;-)

Enjoy,

Greetings /\/\o\/\/

PS. No one the answer yet to my "Piano Challenge" in PoSH Challenge part 6  ?