Add a SIFT example

examples/sift/README.md

@@ -0,0 +1,83 @@
+# Scale-invariant feature transform (SIFT)
+
+This example should demonstrate how to use SIFT to detect matching points in two images. 
+
+```d
+import mir.ndslice;
+import mir.rc;
+
+import dcv.core;
+import dcv.imgproc;
+import dcv.imageio;
+import dcv.plot;
+import dcv.features.sift;
+
+
+// https://github.com/dbarac/sift-cpp/blob/b54827526c6b6bfa71a714950f4654e6ea7ba491/src/sift.cpp
+
+@nogc nothrow:
+
+void main()
+{
+    // read two images to match potential keypoints
+    auto image1 = imread("../data/matching/box.png");
+    auto image2 = imread("../data/matching/box_in_scene.png");
+    scope(exit){ // only class Image requires an explicit free in DCV.
+        destroyFree(image1);
+        destroyFree(image2);
+    }
+
+    // a SIFT keypoint contains both coordinates and a descriptor vector ubyte[128]
+    // First compute them for both images
+    Array!SIFTKeypoint keypoints1 = find_sift_keypoints_and_descriptors(image1.sliced);
+    Array!SIFTKeypoint keypoints2 = find_sift_keypoints_and_descriptors(image2.sliced);
+
+    // show detected keypoints using plot functions of DCV
+    auto fig1 = imshow(image1, "image1");
+    foreach (kp; keypoints1) {
+        fig1.drawCircle(PlotCircle(kp.x, kp.y, 3.0f), plotRed, true);
+    }
+
+    auto fig2 = imshow(image2, "image2");
+    foreach (kp; keypoints2) {
+        fig2.drawCircle(PlotCircle(kp.x, kp.y, 3.0f), plotRed, true);
+    }
+
+    // determine matched points based on the euclidean distance between shape descriptors of SIFTKeypoints
+    auto matches = find_sift_keypoint_matches(keypoints1, keypoints2);
+
+    /+  Draw lines between matched points on the stitched image +/
+
+    // first create an image frame that can contain two images
+    auto stitched = rcslice!ubyte([image1.height + image2.height, image1.width + image2.width, 3], 0);
+    stitched[0..image1.height, 0..image1.width, 0..$] = image1.sliced[]; // overlay image1 on the frame
+    stitched[image1.height..$, image1.width..$, 0..$] = image2.sliced[]; // overlay image2 on the frame
+
+    // use different colors for different matches. Or write a random color generator
+    immutable AColor[8] colors = [aRed,aGreen,aBlue,aWhite,aBlack,aYellow,aCyan,aMagenta];
+
+    size_t colorInd;
+    foreach (kp1i, kp2i; matches) {
+        auto startPoint = keypoints1[kp1i]; // a keypoint from image1
+        auto endPoint = keypoints2[kp2i];   // Corresponding keypoint from image2
+
+        // Adjust the coordinates according to the stitched frame
+        endPoint.y += image1.height;
+        endPoint.x += image1.width;
+
+        // Draw line between matched points
+        putLine(stitched, APoint(startPoint.x, startPoint.y), APoint(endPoint.x, endPoint.y), colors[colorInd++ % 8], 2);
+    }
+
+    imshow(stitched, "stitched");
+
+    waitKey();
+
+    imwrite(stitched, ImageFormat.IF_RGB, "SIFTmatches.png"); // write result on disk
+}
+
+```
+## Result
+![alt tag](SIFTmatches.png)
+
+

examples/sift/dub.json

@@ -0,0 +1,17 @@
+{
+    "authors": [
+        "Ferhat Kurtulmuş"
+    ],
+    "copyright": "Copyright © 2024, Ferhat Kurtulmuş",
+    "description": "Compute SIFT features and do point matching between two images",
+    "license": "boost 1.0",
+    "name": "siftmatching",
+    "dependencies": {
+        "dcv:core": {"path": "../../"},
+        "dcv:plot": {"path": "../../"},
+        "dcv:imageio": {"path": "../../"}
+    },
+    "subConfigurations": {
+        "dcv:plot": "use-glfw-d"
+    }
+}

examples/sift/source/app.d

@@ -0,0 +1,72 @@
+import mir.ndslice;
+import mir.rc;
+
+import dcv.core;
+import dcv.imgproc;
+import dcv.imageio;
+import dcv.plot;
+import dcv.features.sift;
+
+
+// https://github.com/dbarac/sift-cpp/blob/b54827526c6b6bfa71a714950f4654e6ea7ba491/src/sift.cpp
+
+@nogc nothrow:
+
+void main()
+{
+    // read two images to match potential keypoints
+    auto image1 = imread("../data/matching/box.png");
+    auto image2 = imread("../data/matching/box_in_scene.png");
+    scope(exit){ // only class Image requires an explicit free in DCV.
+        destroyFree(image1);
+        destroyFree(image2);
+    }
+
+    // a SIFT keypoint contains both coordinates and a descriptor vector ubyte[128]
+    // First compute them for both images
+    Array!SIFTKeypoint keypoints1 = find_sift_keypoints_and_descriptors(image1.sliced);
+    Array!SIFTKeypoint keypoints2 = find_sift_keypoints_and_descriptors(image2.sliced);
+
+    // show detected keypoints using plot functions of DCV
+    auto fig1 = imshow(image1, "image1");
+    foreach (kp; keypoints1) {
+        fig1.drawCircle(PlotCircle(kp.x, kp.y, 3.0f), plotRed, true);
+    }
+
+    auto fig2 = imshow(image2, "image2");
+    foreach (kp; keypoints2) {
+        fig2.drawCircle(PlotCircle(kp.x, kp.y, 3.0f), plotRed, true);
+    }
+
+    // determine matched points based on the euclidean distance between shape descriptors of SIFTKeypoints
+    auto matches = find_sift_keypoint_matches(keypoints1, keypoints2);
+
+    /+  Draw lines between matched points on the stitched image +/
+
+    // first create an image frame that can contain two images
+    auto stitched = rcslice!ubyte([image1.height + image2.height, image1.width + image2.width, 3], 0);
+    stitched[0..image1.height, 0..image1.width, 0..$] = image1.sliced[]; // overlay image1 on the frame
+    stitched[image1.height..$, image1.width..$, 0..$] = image2.sliced[]; // overlay image2 on the frame
+
+    // use different colors for different matches. Or write a random color generator
+    immutable AColor[8] colors = [aRed,aGreen,aBlue,aWhite,aBlack,aYellow,aCyan,aMagenta];
+
+    size_t colorInd;
+    foreach (kp1i, kp2i; matches) {
+        auto startPoint = keypoints1[kp1i]; // a keypoint from image1
+        auto endPoint = keypoints2[kp2i];   // Corresponding keypoint from image2
+
+        // Adjust the coordinates according to the stitched frame
+        endPoint.y += image1.height;
+        endPoint.x += image1.width;
+
+        // Draw line between matched points
+        putLine(stitched, APoint(startPoint.x, startPoint.y), APoint(endPoint.x, endPoint.y), colors[colorInd++ % 8], 2);
+    }
+
+    imshow(stitched, "stitched");
+
+    waitKey();
+
+    imwrite(stitched, ImageFormat.IF_RGB, "SIFTmatches.png"); // write result on disk
+}

source/dcv/features/package.d

@@ -14,4 +14,4 @@ module dcv.features;
  * other popular feature detectors, descriptor (surf, brief, orb, akaze, etc.)
  */
 
-public import dcv.features.corner, dcv.features.utils;
+public import dcv.features.corner, dcv.features.utils, dcv.features.sift;