Bugfix for flux2 img2img2 prediction (#12855)

* Bugfix for dreambooth flux2 img2img2

* Bugfix for dreambooth flux2 img2img2

* Bugfix for dreambooth flux2 img2img2

* Bugfix for dreambooth flux2 img2img2

* Bugfix for dreambooth flux2 img2img2

* Bugfix for dreambooth flux2 img2img2

Co-authored-by: tcaimm <[email protected]>

---------

Co-authored-by: tcaimm <[email protected]>

Author: leisuzz

examples/dreambooth/train_dreambooth_lora_flux2_img2img.py

@@ -1695,9 +1695,13 @@ def get_sigmas(timesteps, n_dim=4, dtype=torch.float32):
                 cond_model_input = (cond_model_input - latents_bn_mean) / latents_bn_std
 
                 model_input_ids = Flux2Pipeline._prepare_latent_ids(model_input).to(device=model_input.device)
-                cond_model_input_ids = Flux2Pipeline._prepare_image_ids(cond_model_input).to(
+                cond_model_input_list = [cond_model_input[i].unsqueeze(0) for i in range(cond_model_input.shape[0])]
+                cond_model_input_ids = Flux2Pipeline._prepare_image_ids(cond_model_input_list).to(
                     device=cond_model_input.device
                 )
+                cond_model_input_ids = cond_model_input_ids.view(
+                    cond_model_input.shape[0], -1, model_input_ids.shape[-1]
+                )
 
                 # Sample noise that we'll add to the latents
                 noise = torch.randn_like(model_input)
@@ -1724,6 +1728,9 @@ def get_sigmas(timesteps, n_dim=4, dtype=torch.float32):
                 packed_noisy_model_input = Flux2Pipeline._pack_latents(noisy_model_input)
                 packed_cond_model_input = Flux2Pipeline._pack_latents(cond_model_input)
 
+                orig_input_shape = packed_noisy_model_input.shape
+                orig_input_ids_shape = model_input_ids.shape
+
                 # concatenate the model inputs with the cond inputs
                 packed_noisy_model_input = torch.cat([packed_noisy_model_input, packed_cond_model_input], dim=1)
                 model_input_ids = torch.cat([model_input_ids, cond_model_input_ids], dim=1)
@@ -1742,7 +1749,8 @@ def get_sigmas(timesteps, n_dim=4, dtype=torch.float32):
                     img_ids=model_input_ids,  # B, image_seq_len, 4
                     return_dict=False,
                 )[0]
-                model_pred = model_pred[:, : packed_noisy_model_input.size(1) :]
+                model_pred = model_pred[:, : orig_input_shape[1], :]
+                model_input_ids = model_input_ids[:, : orig_input_ids_shape[1], :]
 
                 model_pred = Flux2Pipeline._unpack_latents_with_ids(model_pred, model_input_ids)