[segment-anything] Support multi-point as the prompt input (#945)

* [sam] Support multi-point prompts

* [segment-anything] Pass points by reference

* [segment-anything] Update example code and image

* Fix clippy lint.

---------

Co-authored-by: Yun Ding <yunding@nvidia.com>
Co-authored-by: laurent <laurent.mazare@gmail.com>

candle-examples/examples/segment-anything/README.md

@@ -16,25 +16,30 @@ based on [MobileSAM](https://github.com/ChaoningZhang/MobileSAM).
 cargo run --example segment-anything --release -- \
     --image candle-examples/examples/yolo-v8/assets/bike.jpg
     --use-tiny
-    --point-x 0.4
-    --point-y 0.3
+    --point-x 0.6,0.6
+    --point-y 0.6,0.55
 ```
 
 Running this command generates a `sam_merged.jpg` file containing the original
-image with a blue overlay of the selected mask. The red dot represents the prompt
-specified by `--point-x 0.4 --point-y 0.3`, this prompt is assumed to be part
+image with a blue overlay of the selected mask. The red dots represent the prompt
+specified by `--point-x 0.6,0.6 --point-y 0.6,0.55`, this prompt is assumed to be part
 of the target mask.
 
 The values used for `--point-x` and `--point-y` should be between 0 and 1 and
 are proportional to the image dimension, i.e. use 0.5 for the image center.
 
+Original image:
 ![Leading group, Giro d'Italia 2021](../yolo-v8/assets/bike.jpg)
 
-![Leading group, Giro d'Italia 2021](./assets/sam_merged.jpg)
+Segment results by prompting with a single point `--point-x 0.6 --point-y 0.55`:
+![Leading group, Giro d'Italia 2021](./assets/single_pt_prompt.jpg)
+
+Segment results by prompting with multiple points `--point-x 0.6,0.6 --point-y 0.6,0.55`:
+![Leading group, Giro d'Italia 2021](./assets/two_pt_prompt.jpg)
 
 ### Command-line flags
 - `--use-tiny`: use the TinyViT based MobileSAM backbone rather than the default
   one.
-- `--point-x`, `--point-y`: specifies the location of the target point.
+- `--point-x`, `--point-y`: specifies the location of the target points.
 - `--threshold`: sets the threshold value to be part of the mask, a negative
   value results in a larger mask and can be specified via `--threshold=-1.2`.

candle-examples/examples/segment-anything/main.rs

@@ -27,13 +27,13 @@ struct Args {
     #[arg(long)]
     generate_masks: bool,
 
-    /// The target point x coordinate, between 0 and 1 (0.5 is at the middle of the image).
-    #[arg(long, default_value_t = 0.5)]
-    point_x: f64,
+    /// Comma separated list of x coordinates, between 0 and 1 (0.5 is at the middle of the image).
+    #[arg(long, use_value_delimiter = true)]
+    point_x: Vec<f64>,
 
-    /// The target point y coordinate, between 0 and 1 (0.5 is at the middle of the image).
-    #[arg(long, default_value_t = 0.5)]
-    point_y: f64,
+    /// Comma separated list of y coordinate, between 0 and 1 (0.5 is at the middle of the image).
+    #[arg(long, use_value_delimiter = true)]
+    point_y: Vec<f64>,
 
     /// The detection threshold for the mask, 0 is the default value, negative values mean a larger
     /// mask, positive makes the mask more selective.
@@ -111,9 +111,16 @@ pub fn main() -> anyhow::Result<()> {
             )?;
         }
     } else {
-        let point = Some((args.point_x, args.point_y));
+        if args.point_x.len() != args.point_y.len() {
+            anyhow::bail!(
+                "number of x coordinates unequal to the number of y coordinates: {} v.s. {}",
+                args.point_x.len(),
+                args.point_y.len()
+            );
+        }
+        let points: Vec<(f64, f64)> = args.point_x.into_iter().zip(args.point_y).collect();
         let start_time = std::time::Instant::now();
-        let (mask, iou_predictions) = sam.forward(&image, point, false)?;
+        let (mask, iou_predictions) = sam.forward(&image, &points, false)?;
         println!(
             "mask generated in {:.2}s",
             start_time.elapsed().as_secs_f32()
@@ -151,12 +158,17 @@ pub fn main() -> anyhow::Result<()> {
                 }
             }
         }
-        let (x, y) = (
-            (args.point_x * img.width() as f64) as i32,
-            (args.point_y * img.height() as f64) as i32,
-        );
-        imageproc::drawing::draw_filled_circle(&img, (x, y), 3, image::Rgba([255, 0, 0, 200]))
-            .save("sam_merged.jpg")?
+        for (x, y) in points {
+            let x = (x * img.width() as f64) as i32;
+            let y = (y * img.height() as f64) as i32;
+            imageproc::drawing::draw_filled_circle_mut(
+                &mut img,
+                (x, y),
+                3,
+                image::Rgba([255, 0, 0, 200]),
+            );
+        }
+        img.save("sam_merged.jpg")?
     }
     Ok(())
 }

candle-transformers/src/models/segment_anything/sam.rs

@@ -130,7 +130,7 @@ impl Sam {
     pub fn forward(
         &self,
         img: &Tensor,
-        point: Option<(f64, f64)>,
+        points: &[(f64, f64)],
         multimask_output: bool,
     ) -> Result<(Tensor, Tensor)> {
         let (_c, original_h, original_w) = img.dims3()?;
@@ -140,7 +140,7 @@ impl Sam {
             &img_embeddings,
             original_h,
             original_w,
-            point,
+            points,
             multimask_output,
         )?;
         let mask = low_res_mask
@@ -155,20 +155,24 @@ impl Sam {
         img_embeddings: &Tensor,
         original_h: usize,
         original_w: usize,
-        point: Option<(f64, f64)>,
+        points: &[(f64, f64)],
         multimask_output: bool,
     ) -> Result<(Tensor, Tensor)> {
         let image_pe = self.prompt_encoder.get_dense_pe()?;
-        let points = match point {
-            None => None,
-            Some((x, y)) => {
-                let points = Tensor::new(
-                    &[[[x as f32 * original_w as f32, y as f32 * original_h as f32]]],
-                    img_embeddings.device(),
-                )?;
-                let labels = Tensor::ones((1, 1), DType::F32, img_embeddings.device())?;
-                Some((points, labels))
-            }
+        let points = if points.is_empty() {
+            None
+        } else {
+            let n_points = points.len();
+            let mut coords = vec![];
+            points.iter().for_each(|(x, y)| {
+                let x = (*x as f32) * (original_w as f32);
+                let y = (*y as f32) * (original_h as f32);
+                coords.push(x);
+                coords.push(y);
+            });
+            let points = Tensor::from_vec(coords, (n_points, 1, 2), img_embeddings.device())?;
+            let labels = Tensor::ones((n_points, 1), DType::F32, img_embeddings.device())?;
+            Some((points, labels))
         };
         let points = points.as_ref().map(|(x, y)| (x, y));
         let (sparse_prompt_embeddings, dense_prompt_embeddings) =

candle-wasm-examples/segment-anything/src/bin/m.rs

@@ -94,7 +94,7 @@ impl Model {
             &embeddings.data,
             embeddings.height as usize,
             embeddings.width as usize,
-            Some((x, y)),
+            &[(x, y)],
             false,
         )?;
         let iou = iou_predictions.flatten(0, 1)?.to_vec1::<f32>()?[0];