salient-autofocus

    0.9.1 • Public • Published

    salient-autofocus

    Auto-focus capabilities based on saliency maps.

    Basic Usage

    Extract a 640x480 region from a 1024x768 image using salient auto-focus

    const autoFocus = require('salient-autofocus');
    
    const salientMatrix = [[0, 0.25, 0.5], [0, 0, 0.25], [0, 0.25, 0.75]]; // custom 3x3 matrix
    const region = autoFocus.getRegionFromSalientMatrix(salientMatrix, { imageWidth: 1024, imageHeight: 768, regionWidth: 640, regionHeight: 480 });
    // { left, top, right, bottom, width, height }
    

    OpenCV Usage

    Extract a 640x480 region from a 1024x768 image using salient auto-focus

    const autoFocus = require('salient-autofocus');
    
    const salientMatrix = mySalientMap.getDataAsArray(); // works with opencv or opencv4nodejs packages
    const region = autoFocus.getRegionFromSalientMatrix(salientMatrix, { imageWidth: 1024, imageHeight: 768, regionWidth: 640, regionHeight: 480 });
    // { left, top, right, bottom, width, height }
    

    Production Usage

    The real power of this package is the metadata that it extracts from saliency data, which can be stored or cached, allowing subsequent auto-focus requests to be lightning fast! No need to re-create salient maps, store salient maps, or re-process salient maps.

    const autoFocus = require('salient-autofocus');
    
    const salientMatrix = mySalientMap.getDataAsArray(); // works with opencv or opencv4nodejs packages
    const salientMeta = autoFocus.getMetaFromSalientMatrix(salientMatrix);
    // TODO: store meta for subsequent auto-focus requests
    const region = autoFocus.getRegionFromMeta(salientMeta, { imageWidth: 1024, imageHeight: 768, regionWidth: 640, regionHeight: 480 }); // SUPA FAST!
    // { left, top, right, bottom, width, height }
    

    Where do I get my salient map?

    That's out of the scope of this project as there are many models for generating salient maps based on TONS of research. However you're in luck, because I just happen to author one of those solutions: https://github.com/asilvas/salient-maps

    Example Results

    The following examples are visual representations of the original image side by side with the salient map, overlayed by the regions of saliency density to illustrate where salient-autofocus will focus on depending on the available size of the region requested. The more accurate the saliency map, the better salient-autofocus will perform.

    Region Data

    Data returned by getRegionFromSalientMatrix or getRegionFromMeta to indicate the region to focus on.

    { left, top, right, bottom, width, height }
    
    Property Type Info
    left number Left-most edge of region on a 0 to {imageWidth} scale in columns (typically pixels)
    top number Top-most edge of region on a 0 to {imageHeight} scale in rows (typically pixels)
    width number Width of region on a 0 to {imageWidth} scale in columns (typically pixels)
    height number Height of region on a 0 to {imageHeight} scale in rows (typically pixels)
    right number Right-most edge of region added for convenience (left+width)
    bottom number Bottom-most edge of region added for convenience (top+height)

    Meta Data

    If extracting meta from salient data via getMetaFromSalientMatrix (as you should for production usage), below is the structure of that data for reference.

    {
      v,
      c: {
        x,
        y
      },
      r25th,
      r40th,
      r50th,
      r75th,
      r90th
    }
    
    Property Type Info
    v number Version of the data structure. If this version ever changes, you should consider the old meta invalid
    c object Center point based on average saliency. Typically ignored unless no regions are identified, but still can be useful
    c.x number Center x dimension from 0 (left) to 1 (right)
    c.y number Center y dimension from 0 (top) to 1 (bottom)
    r25th MetaRegion MetaRegion that encompasses ~25% of all saliency
    r40th MetaRegion MetaRegion that encompasses ~40% of all saliency
    r50th MetaRegion MetaRegion that encompasses ~50% of all saliency
    r75th MetaRegion MetaRegion that encompasses ~75% of all saliency
    r90th MetaRegion MetaRegion that encompasses ~90% of all saliency

    Meta Region Data

    The meta region structure used for caching, not to be confused by the Region returned by getRegionFromSalientMatrix or getRegionFromMeta.

    { l, t, w, h }
    
    Property Type Info
    l number Left-most edge of region on a 0 to 1 scale
    t number Top-most edge of region on a 0 to 1 scale
    w number Width of region on a 0 to 1 scale
    h number Height of region on a 0 to 1 scale

    Install

    npm i salient-autofocus

    DownloadsWeekly Downloads

    18

    Version

    0.9.1

    License

    MIT

    Unpacked Size

    21 kB

    Total Files

    8

    Last publish

    Collaborators

    • asilvas