EDIT October 2013: FastPix code modified to handle the Byte Array correctly. See post #38 below.
People are forever complaining about the slowness of GetPixel and SetPixel. They probably weren't designed for processing whole images (or if they were, they were designed very badly). DotNet has an answer to that, but it's not an easy one to get your head around: the Bitmap class methods LockBits and UnlockBits.
The main idea of FastPix is to provide a substitute for GetPixel and SetPixel which seem to work about 10 to 15 times as fast as the original ones. But it has more to offer.
There are plenty of examples on the web of classes that encapsulate LockBits/UnlockBits. The ones I have seen are often hampered because they try to deal with different bitmap formats. But as far as I can see nearly all the bitmaps we deal with are either 24 bits (digital photos, some drawing programs) or 32 bits (drawing programs with transparency). GDI+ converts 24 bit images internally to 32 bits anyway, so I have designed FastPix to work with 32 bits only. It makes the code simpler and opens up the possibility of processing bitmaps as Integer arrays, which are blindingly fast. FastPix includes a ConvertFormat method for converting bitmap pixel formats or you can use:
vb.net Code:
Dim img = Image.FromFile(filename)
Dim bmp As New Bitmap(img)
The bitmap New sub converts a loaded image (but not an image file) to 32 bits.
To start using Fastpix, download the attached zip file and unzip it to a convenient folder. In Visual Studio, select Project/Add Existing Item... and import the unzipped .vb file into your project.
Here is an example of how you use the FastPix GetPixel and SetPixel substitutes. Their format is the same as the ones in the Bitmap class:
vb.net Code:
Using fp as New FastPix(myBitmap)
Dim myColor As Color = fp.GetPixel(x, y)
fp.SetPixel(x, y, Color.Orange)
End Using
Always declare a FastPix object with a Using loop, or otherwise Dispose it as soon as you have finished with it. The UnLockBits is in the Dispose method, so you will not be able to see your resulting bitmap until Dispose has been called either implicitly (with End Using) or directly.
FastPix also offers you the bitmap in the form of an Integer Array and its performance leaves even the Fastpix GetPixel/SetPixel in the dust. Here's an example of how you use it:
vb.net Code:
Using fp as New FastPix(myBitmap)
'Make a local reference to the array; it is roughly 4x as fast as direct references to fp.PixelArray:
Dim pixels as Integer() = fp.PixelArray
For i as integer = 0 to pixels.Length - 1
'example: substitute a color
if pixels(i) = Color.Red.ToArgb then pixels(i) = Color.Blue.ToArgb
'example: invert the color
pixels(i) = pixels(i) XOR $HFFFFFF
Next
End Using
Note how the inversion is done using only a logical instruction and a bit mask. If you can restrict yourself to techniques like that and to integer arithmetic, and avoid all references to objects outside the Class, you can get fantastic performance. For example, inverting the colors of a 10 MP digital photo can be done over 100x as fast as with old-fashioned GetPixel and SetPixel (150x if you don't count the LockBits/UnlockBits overhead).
Of course, many kinds of pixel processing require you to get at the A, R, G and B bytes of the pixel. You can extract those from an integer using the BitConverter.GetBytes method, but that would slow things down terribly. Instead, it is possible to extract the bytes with masks and logic/shift operations only. They are probably just as fast as integer arithmetic. Here is an example which fades a bitmap by leveling all the Alpha byte values to a maximum level:
vb.net Code:
Dim _alpha As Byte 'Level Alpha down to this value
Using fp as New FastPix(myBitmap)
Dim pixels as Integer() = fp.PixelArray
Dim px As Integer = pixels(j)
Dim pxAlpha As Integer = (px >> 24) And &HFF 'shift alpha byte to bottom end, clear rest
If pxAlpha > _alpha Then
pxAlpha = CInt(_alpha) << 24
pixels(j) = (px And &HFFFFFF) Or pxAlpha 'replace original alpha value
End If
End Using
If you don't like the look of that, FastPix also provides a Byte array to make byte operations a bit less intimidating. Possibly it's not as fast as the integer array version. The bytes are in the order B, G, R, A for each pixel. Here's another example of fading a bitmap. Note the extra parameter in the FastPix declaration:
vb.net Code:
Using fp As New FastPix(myBitmap, True)
Dim bytes As byte() = fp.ColorByteArray
'Modify the Alpha bytes to make the bitmap 50% transparent:
For i As Integer = 3 to bytes.Length - 1 Step 4
bytes(i) = 127
Next
End Using
I hope you find it useful. Comments and criticism welcome. BB
Last edited by boops boops; Dec 9th, 2014 at 09:18 AM.
Reason: a few more typos spotted!
Re: FastPix: Rapid Pixel Processing for Dummies and Dudes
Wow, your code looks very lean and effective. How do i apply it to my project so that it can help me sharpen the image using track bar.
Please show me some coding!
Re: FastPix: Rapid Pixel Processing for Dummies and Dudes
Wow. Cant believe that this has so few replies. This is just pure epicness! As you said, the slowness of GetPixel and SetPixel has always annoyed me, this finally fixes this issue. Yay!
Re: FastPix: Rapid Pixel Processing for Dummies and Dudes
@Schravendeel. Thanks for your compliments!
@Moti. Yes, it just stand for the name of your own bitmap. Sorry it wasn't clear.
@Everyone. New version coming soon!
Re: FastPix: Rapid Pixel Processing for Dummies and Dudes
testing report :
form controls :
picturebox : with image in it, streched
button
textbox
code used with fast pix class :
Code:
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim bm As Bitmap
bm = PictureBox1.Image
Using fp As New FastPix(bm)
Dim myColor As Color = fp.GetPixel(20, 20)
fp.SetPixel(20, 20, Color.Orange)
TextBox1.Text = myColor.ToString
End Using
End Sub
End Class
a glitch fired up :
A first chance exception of type 'System.FormatException' occurred in pixelTest1.exe
in the class line (after the if line):
If pFSize <> 32 OrElse bmp.PixelFormat = PixelFormat.Indexed Then
Throw New FormatException _
("FastPix is designed to deal only with 32-bit pixel non-indexed formats. Your bitmap has " _
& pFSize & "-bit pixels. You can convert it using FastPix.ConvertFormat.")
Else
Re: FastPix: Rapid Pixel Processing for Dummies and Dudes
please stop the guessing game
this also glitches:
Code:
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim bm As Bitmap
bm = PictureBox1.Image
Using fp As New FastPix(bm)
FastPix.ConvertFormat(bm, Imaging.PixelFormat.Alpha)
Dim myColor As Color = fp.GetPixel(20, 20)
fp.SetPixel(20, 20, Color.Orange)
TextBox1.Text = myColor.ToString
End Using
End Sub
End Class
Re: FastPix: Rapid Pixel Processing for Dummies and Dudes
You don't seem to get it. I'm not guessing; I'm telling you exactly what you need to hear. You need to convert it before you actually use the image otherwise you'll throw the exception. You know the method to use to perform the conversion, just change where it's being called. It's not that hard.
Re: FastPix: Rapid Pixel Processing for Dummies and Dudes
How is that my problem? That's an exception in System.Drawing.dll, not FastPixel. Try wrapping Try-Catch statements around it and see what you get. Don't get mad at the person that's hand-feeding you help and try using some common logic to fix a problem.
Re: FastPix: Rapid Pixel Processing for Dummies and Dudes
Originally Posted by moti barski
I am not mad at you you're cool the glitches are what got to me
I"ll just hope senior boobs hook me up with a walkthrough
Download the attachment in the first post. The author "boops boops" included a couple of examples in the downloadable file that have be commented out.
when you quote a post could you please do it via the "Reply With Quote" button or if it multiple post click the "''+" button then "Reply With Quote" button.
If this thread is finished with please mark it "Resolved" by selecting "Mark thread resolved" from the "Thread tools" drop-down menu. https://get.cryptobrowser.site/30/4111672
Re: FastPix: Rapid Pixel Processing for Dummies and Dudes
See post #1 in this thread:
Originally Posted by boops boops
nearly all the bitmaps we deal with are either 24 bits (digital photos, some drawing programs) or 32 bits (drawing programs with transparency). GDI+ converts 24 bit images internally to 32 bits anyway, so I have designed FastPix to work with 32 bits only. It makes the code simpler and opens up the possibility of processing bitmaps as Integer arrays, which are blindingly fast. FastPix includes a ConvertFormat method for converting bitmap pixel formats.
Re: FastPix: Rapid Pixel Processing for Dummies and Dudes
Originally Posted by moti barski
and if I had wheels I'd be a wagon
How does that even relate to this situation? You're merely making an analogy that has no reference to the subject at hand. I'm sorry but it wouldn't take very long to work with the code and produce the desired effect you want.
Re: FastPix: Rapid Pixel Processing for Dummies and Dudes
1. download the zip file
2. unzip it to obtain FastPix.vb
3. save the file wherever you like to keep your downloaded code.
4. in Visual Studio, right-click on your project name
5. select Add Existing Item
6. browse to find the FastPix.vb file and select it
7. now you can use Faspix in the project.
Re: FastPix: Rapid Pixel Processing for Dummies and Dudes
Originally Posted by sacramento
Hi:
Thanks for your answear...
I have one doubt her.e..your code could adapt to rotate images or graphics?
It could be used for that in theory, but I doubt if it would be worth the effort. The GDI+ plus methods for rotation (Bitmap.RotateFlip, Graphics.RotateTransform etc.) seem pretty efficient to me. I suppose they use the same Math methods as you would use yourself on an array of pixels.
Re: FastPix: Rapid Pixel Processing for Dummies and Dudes
Hi SaxxonPike,
I compared the "pinned array" method with "lockbits" when I was developing FastPix. It appeared that the pixel processing speed was more or less identical for the two methods, but the instantiation time for the pinned array was much longer, regardless of the bitmap size. I was also uncertain whether the pinned array code might yield problems further down the line (compared to the well-tried lockbits) so I decided to leave it on the shelf.
It's easy to make mistakes when comparing performance, so now (with more experience) I should take a new look at it. Maybe I could try the code you have posted instead of my own version, which was based on a CodeProject example. So thanks for posting it.
Besides, the pinned array approach has significant advantages when you need to process the same bitmap over and over again. Unlike lockbits, you don't have to unlock the bitmap to get at the results so you only have to create the array once. There may also be some advantage to processing the pinned array in an Unsafe block in Csharp, but from what I have read I wouldn't expect it to make a spectacular difference.
Re: FastPix: Rapid Pixel Processing for Dummies and Dudes
Originally Posted by boops boops
Hi SaxxonPike,
I compared the "pinned array" method with "lockbits" when I was developing FastPix. It appeared that the pixel processing speed was more or less identical for the two methods, but the instantiation time for the pinned array was much longer, regardless of the bitmap size. I was also uncertain whether the pinned array code might yield problems further down the line (compared to the well-tried lockbits) so I decided to leave it on the shelf.
My guess would be that the garbage collector has to make special provisions as it cannot do anything with a pinned object. It's really useful if it's something like a screen buffer that won't change for the duration of execution. I am currently using it for a game project and notice no significant slowdowns as a result of creating and disposing bitmaps created in this manner, but I haven't done performance testing extensively as you have.
Doesn't seem like I'm able to edit the code, after throwing it into VB I realized that "Bitmap" was a class name being used as a variable. Whoops The code should work otherwise (if you originally try it, all pixels will have value 0- completely transparent).
Originally Posted by boops boops
There may also be some advantage to processing the pinned array in an Unsafe block in Csharp, but from what I have read I wouldn't expect it to make a spectacular difference.
I thought about using the Unsafe block as I also work with C#; however, that might require special permissions for the end-user and a special configuration for the program. I'm not a big fan of this myself
Re: FastPix: Rapid Pixel Processing for Dummies and Dudes
Originally Posted by SaxxonPike
Doesn't seem like I'm able to edit the code, after throwing it into VB I realized that "Bitmap" was a class name being used as a variable. Whoops The code should work otherwise (if you originally try it, all pixels will have value 0- completely transparent).
Try putting square brackets round the identifier [Bitmap]. BB
How I can display the modified image ( should be shown as 50% transparent, while the pciture in PictureBox2 appear as same as source..i,e PictureBox1)
Should I need to convert the colorbyte array to bmp..or something like that..?
vb.net Code:
PictureBox1.Image = New Bitmap("8.jpg") ' source image
You have discovered an error in FastPix. It seems I never tested the Byte array (ColorByteArray) properly. Thanks for that, and my apologies.
Fortunately it wasn't hard to fix. What I had to do was to declare _UseByteArray at class level, and then test it in the Dispose sub so as to write the correct data to the bitmap.
Code:
'added at Class level
Private _UseByteArray As Boolean
'added in the New sub
_UseByteArray = UseByteArray
'changed in the Dispose sub, instead of only writing _PixelData back to the bitmap:
If _UseByteArray Then
If _ByteData IsNot Nothing Then Marshal.Copy(_ByteData, 0, _bmpData.Scan0, _ByteData.Length)
Else
If _PixelData IsNot Nothing Then Marshal.Copy(_PixelData, 0, _bmpData.Scan0, _PixelData.Length)
End If
There's no need to make these changes yourself. I've posted the corrected FastPix Class as a new attachment to Post #1, because it's easier for people to find there.
There is something else. The bytes in the Btye array are not stored in ARGB order but the reverse BGRA. You have to realize this if you are using the Byte array. Fortunately, the the only change needed in the code is to correct the byte array example in the FastPix comments, as well line 9 of own your code. All that's needed is to change 0 to 3:
Code:
For i As Integer = 3 To bytes.Length -1 Step 4
That will make sure only the A bytes are changed. Make this change, and use the new version of FastPix from post #1, and your code should work ok.
Re: FastPix: Rapid Pixel Processing for Dummies and Dudes
Hi
Something I dont understand well...its my inablity. I was trying to use its different feature.
I wanted to change the pixel color at (x,y) in steps so that it will appear as a uniforn grid (x, y dotted mesh grid line drawn on image..).
The following code does not work (gives error : out of bound of the array). Am I missing something ?
For x As Integer = 0 To pixels.Length - 1 Step 200
For y As Integer = 0 To pixels.Length - 1 Step 200
Dim myColor As Color = fp.GetPixel(x, y)
fp.SetPixel(x, y, Color.Orange)
Next
Next
End Using
PictureBox2.Image = b
while the following code works but the dot in each row shifted so that it seems the lines are drawn diagonally and ofcourse only set of parallel line (diagonally)