added support when gdal metadata present but doesn't include min and max

Author: DanielJDufour

Diff for: index.js

@@ -11,10 +11,12 @@ function sum(array, start, end) {
   return s;
 }
 
-async function getStats(image){
+async function getStats(image, debug){
 
   const fd = image.fileDirectory;
+  if (debug) console.log("fd:", fd);
   const numBands = fd.SamplesPerPixel;
+  if (debug) console.log("numBands:", numBands);
 
   const tileWidth = image.getTileWidth();
   const tileHeight = image.getTileHeight();
@@ -42,6 +44,8 @@ async function getStats(image){
   for (let bandIndex = 0; bandIndex < numBands; bandIndex++) {
     let min = undefined;
     let max = undefined;
+
+    // try to get min and max via GDAL Metadata
     if (fd.GDAL_METADATA) {
       const string = fd.GDAL_METADATA;
       const xmlDom = parseXml(string.substring(0, string.length - 1));
@@ -58,7 +62,9 @@ async function getStats(image){
           }
         }
       }
-    } else {
+    }
+
+    if (min === undefined || max === undefined) {
       for (let rowIndex = 0; rowIndex < numTilesPerCol; rowIndex++) {
         for (let colIndex = 0; colIndex < numTilesPerRow; colIndex++) {
           const reader = sampleReaders[bandIndex];

Diff for: test/test.js

@@ -5,12 +5,12 @@ const { getStats } = require('../index.js');
 
 const SECONDS_TO_MILLISECONDS = 1000;
 
-async function getStatsFromFilepath(filepath) {
+async function getStatsFromFilepath(filepath, debug=false) {
     const data = readFileSync(filepath);
     const arrayBuffer = data.buffer.slice(data.byteOffset, data.byteOffset + data.byteLength);
     const geotiff = await fromArrayBuffer(arrayBuffer);
     const image = await geotiff.getImage();
-    return await getStats(image, true);
+    return await getStats(image, debug);
 }
 
 describe("GeoTIFF.js Test Data", function() {
@@ -29,6 +29,15 @@ describe("GeoTIFF.js Test Data", function() {
     const { bands } = await getStatsFromFilepath('./test/data/GeogToWGS84GeoKey5.tif');
     expect(bands[0].min).to.equal(0);
     expect(bands[0].max).to.equal(2);
+  });
+  it('RGB GeoTIFF that has GDAL Metadata without Stats', async function() {
+    const { bands } = await getStatsFromFilepath('./test/data/rgb_raster.tif');
+    expect(bands[0].min).to.equal(0);
+    expect(bands[0].max).to.equal(182);
+    expect(bands[1].min).to.equal(0);
+    expect(bands[1].max).to.equal(255);
+    expect(bands[2].min).to.equal(0);
+    expect(bands[2].max).to.equal(255);
   })
 });