Add the blip example. (#1144)

* Add the blip example.

* Tweak the example.

* Implement the cross-attn logic.

* Fix some shape mismatches.

* Get some logits out.

* Get some caption to be generated.

candle-examples/examples/blip/main.rs

@@ -0,0 +1,54 @@
+#[cfg(feature = "mkl")]
+extern crate intel_mkl_src;
+
+#[cfg(feature = "accelerate")]
+extern crate accelerate_src;
+
+use clap::Parser;
+
+use candle::DType;
+use candle_nn::VarBuilder;
+use candle_transformers::models::blip;
+
+#[derive(Parser)]
+struct Args {
+    #[arg(long)]
+    model: Option<String>,
+
+    #[arg(long)]
+    image: String,
+
+    /// Run on CPU rather than on GPU.
+    #[arg(long)]
+    cpu: bool,
+}
+
+pub fn main() -> anyhow::Result<()> {
+    let args = Args::parse();
+
+    let device = candle_examples::device(args.cpu)?;
+
+    let image = candle_examples::imagenet::load_image224(args.image)?;
+    println!("loaded image {image:?}");
+
+    let model_file = match args.model {
+        None => {
+            let api = hf_hub::api::sync::Api::new()?;
+            let api = api.repo(hf_hub::Repo::with_revision(
+                "Salesforce/blip-image-captioning-large".to_string(),
+                hf_hub::RepoType::Model,
+                "refs/pr/18".to_string(),
+            ));
+            api.get("model.safetensors")?
+        }
+        Some(model) => model.into(),
+    };
+    let vb = unsafe { VarBuilder::from_mmaped_safetensors(&[model_file], DType::F32, &device)? };
+    let config = blip::Config::image_captioning_large();
+    let model = blip::BlipForConditionalGeneration::new(&config, vb)?;
+    println!("model built");
+    // TODO: Maybe add support for the conditional prompt.
+    let out = model.generate(&image.unsqueeze(0)?, None, None)?;
+    println!(">>>\n{out}");
+    Ok(())
+}