com.googlecode.leptonica.android

Class AdaptiveMap

java.lang.Object

com.googlecode.leptonica.android.AdaptiveMap

public class AdaptiveMap
extends Object

Image adaptive mapping methods.

Author:

alanv@google.com (Alan Viverette)

Constructor Summary

Constructors

Constructor and Description
AdaptiveMap()

Method Summary

Methods

Modifier and Type	Method and Description
static Pix	backgroundNormMorph(Pix pixs) Normalizes an image's background using default parameters.
static Pix	backgroundNormMorph(Pix pixs, int normReduction, int normSize, int normBgValue) Normalizes an image's background to a specified value.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AdaptiveMap

public AdaptiveMap()

Method Detail

backgroundNormMorph

public static Pix backgroundNormMorph(Pix pixs)

Normalizes an image's background using default parameters.

Parameters:

pixs - A source pix image.

Returns:

the source pix image with a normalized background

backgroundNormMorph

public static Pix backgroundNormMorph(Pix pixs,
                      int normReduction,
                      int normSize,
                      int normBgValue)

Normalizes an image's background to a specified value.

Notes:

1. This is a top-level interface for normalizing the image intensity by mapping the image so that the background is near the input value 'bgval'.
2. The input image is either grayscale or rgb.
3. For each component in the input image, the background value is estimated using a grayscale closing; hence the 'Morph' in the function name.
4. An optional binary mask can be specified, with the foreground pixels typically over image regions. The resulting background map values will be determined by surrounding pixels that are not under the mask foreground. The origin (0,0) of this mask is assumed to be aligned with the origin of the input image. This binary mask must not fully cover pixs, because then there will be no pixels in the input image available to compute the background.
5. The map is computed at reduced size (given by 'reduction') from the input pixs and optional pixim. At this scale, pixs is closed to remove the background, using a square Sel of odd dimension. The product of reduction * size should be large enough to remove most of the text foreground.
6. No convolutional smoothing needs to be done on the map before inverting it.
7. A 'bgval' target background value for the normalized image. This should be at least 128. If set too close to 255, some clipping will occur in the result.

Parameters:

pixs - A source pix image.

normReduction - Reduction at which morphological closings are done.

normSize - Size of square Sel for the closing.

normBgValue - Target background value.

Returns:

the source pix image with a normalized background