java.lang.Object
- net.sourceforge.jiu.ops.Operation
- - net.sourceforge.jiu.ops.ImageToImageOperation
  - - net.sourceforge.jiu.color.reduction.RGBToGrayConversion

```
public class RGBToGrayConversion
extends ImageToImageOperation
```
Converts RGB color images (both truecolor and paletted) to grayscale images. The weights to be used with the three base colors red, green and blue can be modified with a call to setColorWeights(float, float, float).
Supported image types
RGB24Image and Paletted8Image can be used as input image types. A Gray8Image be will be created from them.
Could be optimized to use int multiplication instead of float multiplication.
Usage example
Convert some PixelImage rgbImage to grayscale:
```
PixelImage grayImg = RGBToGrayConversion.convert(rgbImage);
```
Using your own color weights can be done like this. You may also want to specify an output grayscale image if you have one to reuse.
```
 RGBToGrayConversion rgbtogray = new RGBToGrayConversion();
 rgbtogray.setInputImage(image);
 rgbtogray.setColorWeights(0.3f, 0.3f, 0.4f);
 rgbtogray.process();
 PixelImage grayImage = rgbtogray.getOutputImage();
 
```
Author:

Marco Schmidt

Field Summary

Fields
Modifier and Type	Field	Description
`private float`	`blueWeight`
`static float`	`DEFAULT_BLUE_WEIGHT`	The default weight for blue samples in the conversion, 0.11f.
`static float`	`DEFAULT_GREEN_WEIGHT`	The default weight for green samples in the conversion, 0.59f.
`static float`	`DEFAULT_RED_WEIGHT`	The default weight for red samples in the conversion, 0.3f.
`private float`	`greenWeight`
`private float`	`redWeight`

Constructor Summary

Constructors
Constructor Description

RGBToGrayConversion()

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`static PixelImage`	`convert(PixelImage rgbImage)`	Static convenience method to convert an RGB image to a grayscale image.
`void`	`process()`	This method does the actual work of the operation.
`private void`	`process(Paletted8Image in)`
`private void`	`process(RGB24Image in)`
`private void`	`process(RGB48Image in)`
`private void`	`process(RGBIntegerImage in, GrayIntegerImage out)`
`void`	`setColorWeights(float red, float green, float blue)`	Sets the weights for the three colors red, green and blue used in the conversion procedure.

Methods inherited from class net.sourceforge.jiu.ops.ImageToImageOperation
canInputAndOutputBeEqual, ensureImagesHaveSameResolution, ensureInputImageIsAvailable, ensureOutputImageResolution, getInputImage, getOutputImage, setCanInputAndOutputBeEqual, setInputImage, setOutputImage

Methods inherited from class net.sourceforge.jiu.ops.Operation
addProgressListener, addProgressListeners, getAbort, removeProgressListener, setAbort, setProgress, setProgress

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - DEFAULT_RED_WEIGHT
```
public static final float DEFAULT_RED_WEIGHT
```
    The default weight for red samples in the conversion, 0.3f.
    
    See Also:
    
    Constant Field Values
  - DEFAULT_GREEN_WEIGHT
```
public static final float DEFAULT_GREEN_WEIGHT
```
    The default weight for green samples in the conversion, 0.59f.
    
    See Also:
    
    Constant Field Values
  - DEFAULT_BLUE_WEIGHT
```
public static final float DEFAULT_BLUE_WEIGHT
```
    The default weight for blue samples in the conversion, 0.11f.
    
    See Also:
    
    Constant Field Values
  - redWeight
```
private float redWeight
```
  - greenWeight
```
private float greenWeight
```
  - blueWeight
```
private float blueWeight
```
- Constructor Detail
  - RGBToGrayConversion
```
public RGBToGrayConversion()
```
- Method Detail
  - convert
```
public static PixelImage convert(PixelImage rgbImage)
                          throws MissingParameterException,
                                 WrongParameterException
```
    Static convenience method to convert an RGB image to a grayscale image.
    
    Parameters:
    
    rgbImage - input RGB image to be converted
    
    Returns:
    
    a new grayscale image, created from the RGB input image
    
    Throws:
    
    MissingParameterException - rgbImage is null
    
    WrongParameterException - rgbImage's type is unsupported
    
    Since:
    
    0.14.2
  - process
```
private void process(RGBIntegerImage in,
                     GrayIntegerImage out)
```
  - process
```
public void process()
             throws MissingParameterException,
                    WrongParameterException
```
    Description copied from class: Operation
    
    This method does the actual work of the operation. It must be called after all parameters have been given to the operation object.
    
    Overrides:
    
    process in class Operation
    
    Throws:
    
    MissingParameterException - if any mandatory parameter was not given to the operation
    
    WrongParameterException - if at least one of the input parameters was not initialized appropriately (values out of the valid interval, etc.)
  - process
```
private void process(Paletted8Image in)
              throws MissingParameterException,
                     WrongParameterException
```
    Throws:
    
    MissingParameterException
    
    WrongParameterException
  - process
```
private void process(RGB24Image in)
              throws WrongParameterException
```
    Throws:
    
    WrongParameterException
  - process
```
private void process(RGB48Image in)
              throws WrongParameterException
```
    Throws:
    
    WrongParameterException
  - setColorWeights
```
public void setColorWeights(float red,
                            float green,
                            float blue)
```
    Sets the weights for the three colors red, green and blue used in the conversion procedure. For each RGB value (r, g, b) to be converted (whether in a truecolor image or in the palette), the formula is gray = r * red + g * green + b * blue. The default values for these weights are DEFAULT_RED_WEIGHT, DEFAULT_GREEN_WEIGHT and DEFAULT_BLUE_WEIGHT. This method lets the user change these values. Each of these arguments must be >= 0.0f and <= 1.0f. The sum of the three must be <= 1.0f. For any resulting gray value to be spread over the complete scale from 0.0f to 1.0f it is preferable for the sum to be equal to or at least close to 1.0f. However, this is not checked. The smaller the sum of the weights is, the darker the resulting gray image will become.
    
    Parameters:
    
    red - weight of the red sample in the conversion, between 0.0f and 1.0f
    
    green - weight of the green sample in the conversion, between 0.0f and 1.0f
    
    blue - weight of the blue sample in the conversion, between 0.0f and 1.0f
    
    Throws:
    
    IllegalArgumentException - if any one of the above mentioned constraints for the arguments is not met

Class RGBToGrayConversion

Supported image types

Usage example

Field Summary

Constructor Summary

Method Summary

Methods inherited from class net.sourceforge.jiu.ops.ImageToImageOperation

Methods inherited from class net.sourceforge.jiu.ops.Operation

Methods inherited from class java.lang.Object

Field Detail

DEFAULT_RED_WEIGHT

DEFAULT_GREEN_WEIGHT

DEFAULT_BLUE_WEIGHT

redWeight

greenWeight

blueWeight

Constructor Detail

RGBToGrayConversion

Method Detail

convert

process

process

process

process

process

setColorWeights