feat: add Iris-3B text-to-image support

README.md

@@ -67,6 +67,7 @@ API and command-line option may change frequently.***
     - [LLaDA-Image](./docs/llada_image.md)
     - [Ming-Image Design](./docs/ming_image.md)
     - [PixArt](./docs/pixart.md)
+    - [Iris-3B](./docs/iris.md)
   - [Image Edit Models](./docs/edit.md)
     - [FLUX.1-Kontext-dev](./docs/kontext.md)
     - [Qwen Image Edit series](./docs/qwen_image_edit.md)

docs/iris.md

@@ -0,0 +1,24 @@
+# How to Use
+
+Iris-3B generates images directly in pixel space and uses Qwen3-VL-4B-Instruct as the text encoder. No VAE is required.
+
+## Download weights
+
+- Download Iris-3B
+    - safetensors: https://huggingface.co/speridlabs/iris-3b/tree/main (`model.safetensors` in the root directory)
+- Download Qwen3-VL-4B-Instruct
+    - safetensors: https://huggingface.co/Comfy-Org/Krea-2/tree/main/text_encoders
+    - gguf: https://huggingface.co/Qwen/Qwen3-VL-4B-Instruct-GGUF/tree/main
+
+## Examples
+
+```
+.\bin\Release\sd-cli.exe --diffusion-model ..\models\diffusion_models\iris-3b.safetensors --llm ..\models\text_encoders\Qwen3-VL-4B-Instruct-Q4_K_M.gguf -p "a lovely cat" --cfg-scale 3 -H 1024 -W 1024 --diffusion-fa
+```
+
+<img width="256" alt="iris-3b example" src="../assets/iris/example.png" />
+
+## Notes
+
+- Width and height must be multiples of 16. Do not pass `--vae`.
+- Captions are limited to 300 tokens including the assistant-turn suffix. Positive and negative prompts use the same template.

src/conditioning/conditioner.hpp

@@ -2012,7 +2012,8 @@ struct LLMEmbedder : public Conditioner {
                    sd_version_is_sefi_image(version) ||
                    sd_version_is_krea2(version) ||
                    sd_version_is_minimax_h3(version) ||
-                   sd_version_is_mage_flow(version)) {
+                   sd_version_is_mage_flow(version) ||
+                   version == VERSION_IRIS) {
             arch = LLM::LLMArch::QWEN3_VL;
         } else if (sd_version_is_z_image(version) || sd_version_is_z_image_l2p(version) || version == VERSION_OVIS_IMAGE || version == VERSION_FLUX2_KLEIN) {
             arch = LLM::LLMArch::QWEN3;
@@ -2138,9 +2139,10 @@ struct LLMEmbedder : public Conditioner {
 
     std::tuple<std::vector<int>, std::vector<float>, std::vector<float>> tokenize(std::string text,
                                                                                   const std::pair<int, int>& attn_range,
-                                                                                  size_t min_length = 0,
-                                                                                  size_t max_length = 100000000,
-                                                                                  bool spell_quotes = false) {
+                                                                                  size_t min_length         = 0,
+                                                                                  size_t max_length         = 100000000,
+                                                                                  bool spell_quotes         = false,
+                                                                                  const std::string& suffix = "") {
         std::vector<std::pair<std::string, float>> parsed_attention;
         if (attn_range.first >= 0 && attn_range.second > 0) {
             if (attn_range.first > 0) {
@@ -2185,6 +2187,20 @@ struct LLMEmbedder : public Conditioner {
             weights.insert(weights.end(), curr_tokens.size(), curr_weight);
         }
 
+        if (!suffix.empty()) {
+            std::vector<int> suffix_tokens;
+            if (!tokenizer->encode(suffix, suffix_tokens) || suffix_tokens.size() >= max_length) {
+                return {};
+            }
+            // Reserve the assistant-turn marker before truncating the caption.
+            if (tokens.size() > max_length - suffix_tokens.size()) {
+                tokens.resize(max_length - suffix_tokens.size());
+                weights.resize(tokens.size());
+            }
+            tokens.insert(tokens.end(), suffix_tokens.begin(), suffix_tokens.end());
+            weights.insert(weights.end(), suffix_tokens.size(), 1.f);
+        }
+
         std::vector<float> mask;
         tokenizer->pad_tokens(tokens, &weights, &mask, min_length, max_length);
 
@@ -2207,8 +2223,10 @@ struct LLMEmbedder : public Conditioner {
                                     bool spell_quotes                                       = false,
                                     int max_length                                          = 100000000,
                                     const LLM::DeepStackImageEmbeds& deepstack_image_embeds = {},
-                                    const std::vector<LLM::ImageGrid>& image_grids          = {}) {
-        auto tokens_weights_mask = tokenize(prompt, prompt_attn_range, min_length, max_length, spell_quotes);
+                                    const std::vector<LLM::ImageGrid>& image_grids          = {},
+                                    const std::string& prompt_suffix                        = "",
+                                    sd::Tensor<float>* output_mask                          = nullptr) {
+        auto tokens_weights_mask = tokenize(prompt, prompt_attn_range, min_length, max_length, spell_quotes, prompt_suffix);
         auto& tokens             = std::get<0>(tokens_weights_mask);
         auto& weights            = std::get<1>(tokens_weights_mask);
         auto& mask               = std::get<2>(tokens_weights_mask);
@@ -2271,6 +2289,12 @@ struct LLMEmbedder : public Conditioner {
                                                 1);
         }
 
+        if (output_mask != nullptr) {
+            *output_mask = sd::Tensor<float>::zeros({new_hidden_states.shape()[1]});
+            for (size_t i = prompt_template_encode_start_idx; i < mask.size(); ++i) {
+                output_mask->data()[i - prompt_template_encode_start_idx] = mask[i];
+            }
+        }
         return new_hidden_states;
     }
 
@@ -2337,6 +2361,8 @@ struct LLMEmbedder : public Conditioner {
         int hidden_states_min_length         = 0;  // zero pad hidden_states
         bool spell_quotes                    = false;
         std::set<int> out_layers;
+        std::string prompt_suffix;
+        sd::Tensor<float> text_mask;
 
         int64_t t0                     = ggml_time_ms();
         RefImageResizeMode resize_mode = conditioner_params.ref_image_params.vlm_resize_mode;
@@ -3086,6 +3112,23 @@ struct LLMEmbedder : public Conditioner {
             SDCondition result;
             result.c_crossattn = std::move(hidden_states);
             return result;
+        } else if (version == VERSION_IRIS) {
+            prompt =
+                "<|im_start|>system\n"
+                "Describe the image by detailing the color, shape, size, texture, quantity, text, spatial "
+                "relationships of the objects and background:<|im_end|>\n<|im_start|>user\n";
+            auto prefix_tokens = std::get<0>(tokenize(prompt, {0, 0}));
+            if (prefix_tokens.empty()) {
+                return {};
+            }
+            prompt_template_encode_start_idx = static_cast<int>(prefix_tokens.size());
+            hidden_states_min_length         = 300;
+            max_length                       = prompt_template_encode_start_idx + hidden_states_min_length;
+            out_layers                       = {2, 5, 8, 11, 14, 17, 20, 23, 26, 29, 32, 35};
+            prompt_attn_range.first          = static_cast<int>(prompt.size());
+            prompt += conditioner_params.text;
+            prompt_attn_range.second = static_cast<int>(prompt.size());
+            prompt_suffix            = "<|im_end|>\n<|im_start|>assistant\n";
         } else {
             GGML_ABORT("unknown version %d", version);
         }
@@ -3101,7 +3144,9 @@ struct LLMEmbedder : public Conditioner {
                                            spell_quotes,
                                            max_length,
                                            deepstack_image_embeds,
-                                           image_grids);
+                                           image_grids,
+                                           prompt_suffix,
+                                           version == VERSION_IRIS ? &text_mask : nullptr);
         if (hidden_states.empty()) {
             return {};
         }
@@ -3166,6 +3211,7 @@ struct LLMEmbedder : public Conditioner {
         SDCondition result;
         result.c_crossattn        = std::move(hidden_states);
         result.extra_c_crossattns = std::move(extra_hidden_states_vec);
+        result.c_vector           = std::move(text_mask);
         if (version == VERSION_QWEN_IMAGE_2_1) {
             auto slots = sd::Tensor<int32_t>::zeros({result.c_crossattn.shape()[1]});
             for (size_t i = 0; i < image_embeds.size(); ++i) {

src/model.h

@@ -65,6 +65,7 @@ enum SDVersion {
     VERSION_PIXART,
     VERSION_MING_IMAGE,
     VERSION_Z_IMAGE_L2P,
+    VERSION_IRIS,
     VERSION_COUNT,
 };
 
@@ -334,7 +335,8 @@ static inline bool sd_version_is_dit(SDVersion version) {
         sd_version_is_krea2(version) ||
         sd_version_is_mage_flow(version) ||
         sd_version_is_sensenova_u1(version) ||
-        sd_version_is_pixart(version)) {
+        sd_version_is_pixart(version) ||
+        version == VERSION_IRIS) {
         return true;
     }
     return false;