GAMBAS BOOK 3.19.1

This class implements an image as an image. The image content is stored in the process memory, not in the display server like a picture.

To obtain or set individual pixel values, you can treat the Image class as a two-dimensional array: Image[x,y] would refer to the pixel at position (x, y) within the image. All methods change the image and return themselves. However, this does not apply to the Copy() method.

The Image class has these two integer constants:

Table 23.4.2.3.1 : Constants of the Image class

The static property Debug defines the debugging mode or returns the boolean value whether the debugging mode is activated or not. If the debugging mode is activated, a message is displayed on the standard error output for each internal image conversion.

The Image class (gb.image) has these properties:

Table 23.4.2.3.2 : Properties of the Image class

Notes

• Pixels: The pixel format of the returned data depends on which toolkit or library is used. To determine the pixel format, read the Format property. Changing the returned array has no effect on the original image data.
• For more information on pixel formats, see 'Image Management in Gambas' (https://gambaswiki.org/wiki/doc/imageconv).

The Image class has these methods:

Table 23.4.2.3.3 : Methods of the Shape class

Notes

• DrawImage (…): If W and H differ from SrcWidth, SrcHeight, the source image is scaled. SrcX, SrcY, SrcWidth, SrcHeight determine the part of the image to be copied. By default, the entire image is copied.

• Mask(): For example, if the red component of colour is 0, the red value of all pixels is deleted; if the red component of colour is 255, the red value of all pixels remains unchanged; if the red component is between 0 and 255, the red value of all pixels is reduced proportionally. In other words: pixel component = pixel component * colour component / 255. The same procedure applies to the blue, green and alpha components.

An example is presented for each of the above methods of the Image (gb.image) class. If the methods use parameters, these and the images - the original and the modified one - are displayed. The source code used in each case is also shown in extracts.

Example 1 - Image.Desaturate() method

The method converts the original into a greyscale image. Note: The Gray() method is considered obsolete and should be replaced by the Desaturate() method.

Figure 23.4.2.3.1: Desaturate() method

Source code snippet

Public Sub btnDoGray_Click()
 
    lblChanged.Text = "C H A N G E D  >>  " & "G R A Y S C A L E ( )"
'-- imgChanged = imgOriginal.Gray()
'-- Warning: Image.Gray is deprecated, use Image.Desaturate instead.
    imgChanged = imgOriginal.Desaturate()
    pboxChanged.Picture = imgChanged.Picture
 
End

Example 2 - Method mix

In this example, 6 methods are used to manipulate the original one after the other:

Figure 23.4.2.3.2: Method_mix (balance)

Source code snippet

Public Sub btnDoBalanceMix_Click()
 
    imgChanged = imgOriginal
 
    imgChanged = imgChanged.Brightness(-0.2)
    imgChanged = imgChanged.Contrast(0.4)
    imgChanged = imgChanged.Saturation(-0.1)
    imgChanged = imgChanged.Lightness(0.3)
    imgChanged = imgChanged.Hue(-0.4)
    imgChanged = imgChanged.Gamma(-0.33)
 
    pboxChanged.Picture = imgChanged.Picture
 
End

Example 3 - Image.Implode(…) method

The method gives the original an effect that appears to implode the image content in the centre:

Figure 23.4.2.3.3: Implode() method

Source code snippet

  lblChanged.Text = "C H A N G E D  >>  " & "I M P L O D E (...)"
  lblValue.Text = hSliderV.Value / 100
  imgChanged = imgOriginal.Implode(hSliderV.Value / 100, Color.Red)
  pboxChanged.Picture = imgChanged.Picture