Generative image semantic communication converts an image into a text description and then performs text-to-image reconstruction at the receiver via diffusion-based generative models. This paradigm has attracted broad attention due to its extremely low bandwidth cost. However, existing methods still face two critical bottlenecks across image-to-text (I2T) semantic extraction at the transmitter and text-to-image (T2I) semantic reconstruction at the receiver: (i) semantic loss and distortion in I2T, where holistic image descriptions may omit fine-grained object attributes and spatial-position information, causing the generated text to deviate from the original image semantics; and (ii) insufficient semantic faithfulness in T2I, where even with the same semantically faithful text description, different initial noise settings may lead diffusion-based reconstruction to produce images with different levels of semantic consistency with the original image. These issues jointly limit the semantic faithfulness of image reconstruction. To address them, we propose TISC, a text-driven image semantic communication framework tailored for faithful reconstruction. TISC incorporates two key designs: (1) Tree-Structured Attribute Semantic Extraction (TSASE), which decomposes semantic extraction into global scene, background, and object-level attribute descriptions, covering spatial position, shape/pose, color, material, and other physical attributes for each detected object; and (2) an Initial Noise Optimization (INO) mechanism, which selects an initial noise seed at the transmitter according to a comprehensive similarity score that jointly considers visual and semantic consistency. Experiments on multiple datasets show that TSASE improves object-position recovery and semantic description faithfulness, while the INO parameter study supports the adopted configuration for noise selection.
Figures & tables
Fig. 1: Comparative illustrations of conventional methods versus our generative semantic communication framework from two aspects: (a) I2T semantic distortion: conventional methods may suffer from attribute-level semantic distortions such as missing or incorrect color and spatial information, which impair semantic extraction, while our approach mitigates such distortions and improves the reliability of semantic extraction; (b) insufficient semantic faithfulness in T2I reconstruction: conventional methods randomly sample the initial noise, so different noises may lead to reconstruction results with different semantic faithfulness even under the same text description. The proposed method evaluates multiple candidate initial noises at the transmitter and selects the one that produces the most faithful reconstruction within the candidate set.
Fig. 2: Overall architecture of the proposed TISC framework. At the transmitter, TSASE extracts the structured semantic description D , while INO selects the initial noise seed s∗ . These two components are introduced in Sections II and III , respectively. The communication network delivers D and s∗ to the receiver, where they are used to guide LLM-grounded Diffusion-based image reconstruction.
Fig. 3: Example of the tree-structured attribute semantic extraction process.
Fig. 4: An example of the structured semantic description produced by TSASE.
Fig. 5: Illustration of IoU calculation for spatial matching. (a) Original image, where the yellow box denotes the bounding box bi provided by the spatial-position attribute of the i -th object description diS . (b) Candidate reconstruction, where the blue box denotes the bounding box bj′ provided by the spatial-position attribute of the j -th object description d′jS . (c) Spatial overlap between bi and bj′ , which is used to compute their IoU.
Fig. 6: Illustration of matched, missed, and hallucinated objects based on spatial matching. The left panel shows the original image, and the right panel shows the reconstructed image. Green boxes indicate matched objects that appear in both images with sufficient spatial overlap. The red box indicates a missed object that appears only in the original image, while the orange box indicates a hallucinated object that appears only in the reconstructed image.
Fig. 7: Comparison of average IoU between TISC and the w/o TSASE ablation across tested datasets.
Fig. 8: Average TIFA scores ( TIFA ) of TISC and w/o TSASE across five tested datasets.
Fig. 9: TIFA evaluation pipeline.
Fig. 10: Empirical distribution of comprehensive similarity scores induced by random initial noise seeds. The three subfigures correspond to COCO image IDs 99, 93, and 71, respectively. For each image, we fix the semantic description, generation model, and inference configuration, and generate 500 candidate reconstructions using 500 different initial noise seeds. The comprehensive similarity score of each candidate is computed according to Eq. ( 6 ). The blue histogram shows the empirical distribution of the 500 comprehensive similarity scores, where the y-axis denotes probability density rather than sample count, computed as the bin count divided by the product of the total number of samples and the bin width, so that the total area of the histogram is normalized to one. The x-axis represents the comprehensive similarity score. The red curve shows the Gaussian distribution fitted using the empirical mean and standard deviation of the comprehensive similarity scores.
Fig. 11: MLLM-guided evaluation of different weighting configurations.
Fig. 12: End-to-end noise robustness comparison over an AWGN channel. To characterize the channel resource usage of different schemes, we report the average number of channel symbols used per image. For TISC and the JPEG baseline, this number is counted from the output symbols after BPSK modulation. For DeepJSCC, since its end-to-end model implicitly includes source coding, channel coding, and modulation-related operations, we directly count the number of channel symbols produced by its encoder. Under this experimental setting, TISC, the JPEG baseline, and DeepJSCC use approximately 12.6k, 72.2k, and 16.4k channel symbols per image on average, respectively. This indicates that the performance advantage of TISC is not obtained by using more channel resources.
Appendix figures & tables1 asset
Supplementary material from the paper’s appendix.
Appendix
Fig. 13: Comparison between JPEG-based image transmission and the proposed text-driven semantic transmission scheme in terms of compressed bits and the comprehensive similarity score. The x-axis reports the average number of compressed bits per image, and the y-axis reports the dataset-level average comprehensive similarity score computed according to Eq. 6 .
School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen 518172, China · XJTU-POLIMI Joint School, Xi’an Jiaotong University, Xi’an 710049, China · Shenzhen Future Network of Intelligence Institute (FNii-Shenzhen)
School of Computer Science and Information Engineering, Hefei University of Technology, Hefei, China · School of Computer and Artificial Intelligence, Liaoning Normal University, Dalian, China