Re: Converting a JPG to TIF in C#
- From: "Joe Ross" <joeross7@xxxxxxxxxxx>
- Date: Mon, 18 Jul 2005 10:47:47 -0400
Not at all. Glad I could give back to the group as I definitely "took" to
get started on the code.
"Bob Powell [MVP]" <bob@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:OM7d$QLiFHA.2360@xxxxxxxxxxxxxxxxxxxxxxx
> Thanks for this. Would you mind if I post it on Tips and Tricks? I'll
> credit you obviously.
>
> --
> Bob Powell [MVP]
> Visual C#, System.Drawing
>
> Ramuseco Limited .NET consulting
> http://www.ramuseco.com
>
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> "Joe Ross" <joeross7@xxxxxxxxxxx> wrote in message
> news:uF5%23$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);
>> }
>>
>>
>
>
.
- References:
- Converting a JPG to TIF in C#
- From: Joe Ross
- Re: Converting a JPG to TIF in C#
- From: Bob Powell [MVP]
- Converting a JPG to TIF in C#
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