Re: Converting a JPG to TIF in C#
- From: "Bob Powell [MVP]" <bob@xxxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Thu, 14 Jul 2005 22:41:56 +0200
Thanks for this. Would you mind if I post it on Tips and Tricks? I'll credit
you obviously.
--
Bob Powell [MVP]
Visual C#, System.Drawing
Ramuseco Limited .NET consulting
http://www.ramuseco.com
Find great Windows Forms articles in Windows Forms Tips and Tricks
http://www.bobpowell.net/tipstricks.htm
Answer those GDI+ questions with the GDI+ FAQ
http://www.bobpowell.net/faqmain.htm
All new articles provide code in C# and VB.NET.
Subscribe to the RSS feeds provided and never miss a new article.
"Joe Ross" <joeross7@xxxxxxxxxxx> wrote in message
news:uF5%23$YKiFHA.2152@xxxxxxxxxxxxxxxxxxxxxxx
>I needed to create a batch process to convert a large number of JPGs to TIF
>CCIT4 format. I'm sure there are libraries out there to do this, but I
>couldn't find any that were free. I also found lots of source code that
>got me on the right track but never seemed to solve my problem completely.
>So I implemented my solution, it works, and I thought I would share it with
>this group as I was helped by the group (especially Bob Powell's posts and
>website). I thought something like this would be built into the framework.
>Maybe it is and I just missed it. If there's an easier way, I'd love to
>hear how. This solution is works for my scenario, and I also ran it
>through a profiler (ANTS Profiler) to tighten things up a bit (made a huge
>difference).
>
> Good luck!
> -joe
>
> Here's the C# code:
> /********************************************/
> private static void ConvertJPGtoTIF (string jpgPath, string tifPath,
> ImageCodecInfo ici)
> {
> byte tifPixels = 0;
> float[] brightnessValues;
>
> Bitmap jpgImage;
> Bitmap tifImage;
> BitmapData jpgBmd;
> BitmapData tifBmd;
> Color[] entries;
> EncoderParameters eps = new EncoderParameters(1);
>
> // new up a Bitmap from the source JPG file then
> // get the bytes of the jpg so we can read through them
> // 8 bits or 1 byte of the jpg is equal to 1 pixel
> // each byte represents a color value that is in the Bitmaps Palette
> jpgImage = new Bitmap (jpgPath);
> jpgBmd = jpgImage.LockBits (
> new Rectangle (0, 0, jpgImage.Width, jpgImage.Height),
> ImageLockMode.ReadOnly,
> PixelFormat.Format8bppIndexed);
>
> // new up a Bitmap that will hold our destination TIF file then
> // get the bytes of the tif so we can write to them
> // 8 bits or 1 byte of the tif is equal to 8 pixels (i.e. 1 bit of the
> tif is equal to 1 pixel)
> tifImage = new Bitmap (jpgImage.Width, jpgImage.Height,
> PixelFormat.Format1bppIndexed);
> tifBmd = tifImage.LockBits (
> new Rectangle (0, 0, tifImage.Width, tifImage.Height),
> ImageLockMode.WriteOnly,
> PixelFormat.Format1bppIndexed);
>
> // we will be doing a lookup into Palette.Entries for the color
> reference by the JPG pixel
> // Entries is a collection of Color objects that is generated each time
> Palette.Entries is called
> // I originally had this code inside the loop, but that was obviously
> extremely inefficient once
> // I realized how it was working. I then discovered that the
> GetBrightness() call seems to be
> // calculated on each call also. So since I only need the brightness
> value from each color,
> // I stuck those values in an array of floats that I would go after in
> the loop
> entries = jpgImage.Palette.Entries;
> brightnessValues = new float[entries.Length];
> for (int index = 0; index < entries.Length; index++)
> brightnessValues[index] = entries[index].GetBrightness ();
>
> // starting point from http://www.bobpowell.net/lockingbits.htm and
> Bob's newsgroup posts...thanks Bob!
> // for understanding of Stride see Bob's site - basically, the image is
> wider in memory than the actual width
> for (int h = 0; h < jpgBmd.Height; h++) // iterate through all of the
> rows of the JPG
> for (int w = 0; w < jpgBmd.Stride; w++) // iterate through all of
> the columns for the current row of the JPG
> {
> // 1 byte of the jpg is 1 pixel
> byte jpgPixel = Marshal.ReadByte (jpgBmd.Scan0, h *
> jpgBmd.Stride + w);
>
> // get the brightness/luminescence HSB/L value for a good
> conversion to black or white
> // using .5 as black = 0.0 and white = 1.0
> bool isWhitePixel = brightnessValues[jpgPixel] < 0.5 ? false :
> true;
>
> // we need to translate what we know about this JPG pixel
> (white or black) to the correct
> // bit in the current byte of the TIF pixel
> // the whole 7- thing is for writing the bits left to right
> // only do this work if it's white, otherwise the bit is
> already 0 from the reset below
> if (isWhitePixel)
> tifPixels = (byte)(tifPixels | (1 << (7-(w % 8))));
> if (w % 8 == 7) // we only write out TIF bytes after every 8
> JPG bytes
> {
> // divide width by 8 for proper TIF pixel
> Marshal.WriteByte (tifBmd.Scan0, h * tifBmd.Stride + w/8,
> tifPixels);
> tifPixels = 0; // reset is needed since we are not ORing 0s
> in
> }
> }
> jpgImage.UnlockBits (jpgBmd);
> tifImage.UnlockBits (tifBmd);
>
> // save it out as a CCITT4 compressed TIF
> eps.Param[0] = new EncoderParameter (Encoder.Compression,
> (long)EncoderValue.CompressionCCITT4);
> tifImage.Save (tifPath, ici, eps);
> }
>
>
.
- Follow-Ups:
- Re: Converting a JPG to TIF in C#
- From: Joe Ross
- Re: Converting a JPG to TIF in C#
- References:
- Converting a JPG to TIF in C#
- From: Joe Ross
- Converting a JPG to TIF in C#
- Prev by Date: Converting a JPG to TIF in C#
- Next by Date: Generic Error in GDI+ related to DrawLine
- Previous by thread: Converting a JPG to TIF in C#
- Next by thread: Re: Converting a JPG to TIF in C#
- Index(es):
Relevant Pages
|
