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5.4 Format

These are operations which change an object's format in some way.

Convert_format_to
These items change number representation. For images, they change the meaning and number of bits in the file. For other objects they trim the range and accuracy of value.

Scale_to_byte
This searches an object for the minimum and maximum value, calculates a linear (scale and offset) transformation which will move the min and max to the range 0-255, and returns the scaled object.

Convert_to_matrix
This examines the object and tries to build a matrix from it. This will only work for small images: it is very inefficient to represent an image as a matrix.

Convert_to_image
This examines the object and tries to build an image from it.

Matrix_from_colour_chart
This takes a trimmed image of a colour chart (a rectangular grid of coloured squares), measures the average pixel value in the centre 50% of each square, and returns a matrix of the measured values. It assumes the chart is 6 $\times()$ 4 patches (the size of a Macbeth Color Checker Chart): for other size charts, open the row and change the dimensions.

Colour_chart_from_matrix
This takes a matrix of colour measurements and builds a synthetic chart image. It assumes the chart is 6 $\times()$ 4 patches (the size of a Macbeth Color Checker Chart): for other size charts, open the row and change the dimensions.

Colour_from_image
This takes the average of each band of an image and builds a colour object for that average.

Colour_from_image
This builds a small image from a colour object.

Decompose
This examines a compound object and tries to break it into a list of smaller objects. A matrix becomes a list of vectors, an $n$ band image becomes a list of $n$ 1 band images, and so on.

Compose
This takes a list of objects and tries to join them together to make a compound object. A list of numbers become a vector, a $n$ 1 band images become a $n$ band image, and so on.


next up previous contents
Next: 5.5 Histogram Up: 5. Image processing menus Previous: 5.3 Filter   Contents
John Cupitt 2003-07-21