//! Loss functions for classification, detection, and segmentation heads.
//!
//! Provides:
//! - **`focal`**: sigmoid (binary) and softmax (multiclass) focal loss
//! (Lin et al. 2017) for class-imbalanced dense prediction.
//! - **`dice`**: soft Dice / V-Net Dice loss (Milletari et al. 2016) for
//! overlap-based segmentation training.
//! - **`quality`**: reconstruction / image-quality metrics — MSE, PSNR, SSIM,
//! MS-SSIM (also usable as differentiable training objectives).
//!
//! IoU-family bounding-box regression losses live in
//! [`crate::detection::iou_losses`].
pub use ;
pub use ;
pub use ;