Package org.apache.sis.image
Class Interpolation
Object
Interpolation
Algorithm for image interpolation (resampling). Interpolations are performed by sampling on a regular grid
 of pixels using a local neighborhood. The sampling is performed by the 
ResampledImage class, which
 gives the sample values to the interpolate(…) method of this interpolation.
 All methods in this class shall be safe for concurrent use in multi-threading context. For example, interpolations may be executed in a different thread for each tile in an image.
This class is designed for interpolations in a two-dimensional space only.
- Since:
- 1.1
Defined in the sis-feature module
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Field SummaryFieldsModifier and TypeFieldDescriptionstatic final InterpolationA bilinear interpolation using 2×2 pixels.static final InterpolationLanczos interpolation for photographic images.static final InterpolationA nearest-neighbor interpolation using 1×1 pixel.
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Constructor SummaryConstructors
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Method SummaryModifier and TypeMethodDescriptionabstract DimensionReturns the size of the area over which the resampling function needs to provide values.abstract voidinterpolate(DoubleBuffer source, int numBands, double xfrac, double yfrac, double[] writeTo, int writeToOffset) Interpolates sample values for all bands using the given pixel values in local neighborhood.
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Field Details- 
NEARESTA nearest-neighbor interpolation using 1×1 pixel.
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BILINEARA bilinear interpolation using 2×2 pixels. If the interpolation result is NaN, this method fallbacks on nearest-neighbor.
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LANCZOSLanczos interpolation for photographic images. This interpolation is not recommended for images that may contain NaN values.- See Also:
 
 
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Constructor Details- 
Interpolationprotected Interpolation()Creates a new interpolation.
 
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Method Details- 
getSupportSizeReturns the size of the area over which the resampling function needs to provide values. Common values are:Common support sizes Interpolation Width Height Nearest-neighbor 1 1 Bilinear 2 2 Bicubic 4 4 Lanczos 4 4 - Returns:
- number of sample values required for interpolations.
 
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interpolatepublic abstract void interpolate(DoubleBuffer source, int numBands, double xfrac, double yfrac, double[] writeTo, int writeToOffset) Interpolates sample values for all bands using the given pixel values in local neighborhood. The givensourceis a buffer with the number of elements shown below, where support width and support height are given bygetSupportSize():(number of bands) × (support width) × (support height) Values insourcebuffer are always given with band index varying fastest, then column index, then row index. Columns are traversed from left to right and rows are traversed from top to bottom (SequenceType.LINEARiteration order).The interpolation point is in the middle. For example if the support size is 4×4 pixels, then the interpolation point is the dot below and the fractional coordinates are relative to the horizontal and vertical lines drawn below. This figure is for an image with only one band, otherwise all indices between brackets would need to be multiplied by numBands.
 On output, this method shall write the interpolation results ass[0] s[1] s[2] s[3] s[4] s[5]───s[6] s[7] ← yfrac = 0 │ ● ← yfrac given s[8] s[9] s[10] s[11] ← yfrac = 1 s[12] s[13] s[14] s[15] ↑ xfracnumBandsconsecutive values in the suppliedwriteToarray, starting atwriteToOffsetindex. This method should not modify the buffer position (useDoubleBuffer.mark()andreset()if needed).- Parameters:
- source- pixel values from the source image to use for interpolation.
- numBands- number of bands. This is the number of values to put in the- writeToarray.
- xfrac- the X subsample position, usually (but not always) in the range [0 … 1).
- yfrac- the Y subsample position, usually (but not always) in the range [0 … 1).
- writeTo- the array where this method shall write interpolated values.
- writeToOffset- index of the first value to put in the- writeToarray.
 
 
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