LosslessJpegTransform.WriteCropped Method (String, Rectangle)

Syntax

Public Sub WriteCropped ( _
	fileName As String, _
	rectangle As Rectangle _
)

public void WriteCropped(
	string fileName,
	Rectangle rectangle
)

Remarks

You can use this method to recompress only a part of an image. For example, let's assume you want to apply a watermark to an image or remove an effect of red eyes. It obviously makes sense to recompress only that part of image which you modify without recompressing the other parts. It can be easily achieved with the following algorithm:

1. Determine what part of image you need to change. You may need to load it into a bitmap so that the user could select this part manually, or calculate it somehow else.
2. Create LosslessJpegTransform and open it using the Open(String) method.
3. Use AlignToSampleSize(Point, Bitmap) to align the rectangle specifying the image part to JPEG sample size (see below).
4. Use the WriteCropped(Stream, Rectangle) to get a portion of JPEG without recompression.
5. Create a new Bitmap instance and load the resulting JPEG file into it (e.g. using the Load(String) method).
6. Apply the necessary effect to the bitmap (e.g. watermark, red eye removal, etc).
7. Use the WritePatched(String, Point, Bitmap) method to store the resulting bitmap into a JPEG file. Graphics Mill for .NET will automatically compress this bitmap with the same compression options as the original JPEG file and overwrite the appropriate portion of compressed JPEG data.
8. Do not forget to close the LosslessJpegTransform with the Close() method.

See Also

Reference

• LosslessJpegTransform Class
• WriteCropped Overload
• Aurigma.GraphicsMill.Codecs Namespace
• LosslessJpegTransform.AlignToSampleSize(Rectangle, JpegAlignToSampleSizeMode)
• LosslessJpegTransform.Write(String)
• LosslessJpegTransform.WritePatched(String, Point, Bitmap)
• LosslessJpegTransform.WriteRotated(String, RotateFlipType)
• LosslessJpegTransform.WriteTransposed(String)
• LosslessJpegTransform.WriteTransversed(String)