28 June 2022 in IEEE Transactions on Pattern Analysis and Machine Intelligence
Generating photo-realistic images from labels (e.g., semantic labels or sketch labels) is much more challenging than the general image-to-image translation task, mainly due to the large differences between extremely sparse labels and detail rich images. We propose a general framework Lab2Pix to tackle this issue from two aspects: 1) how to extract useful information from the input; and 2) how to efficiently bridge the gap between the labels and images. Specifically, we propose a Double-Guided Normalization (DG-Norm) to use the input label for semantically guiding activations in normalization layers, and use global features with large receptive fields for differentiating the activations within the same semantic region. To efficiently generate the images, we further propose Label Guided Spatial Co-Attention (LSCA) to encourage the learning of incremental visual information using limited model parameters while storing the well-synthesized part in lower-level features. Accordingly, Hierarchical Perceptual Discriminators with Foreground Enhancement Masks are proposed to toughly work against the generator thus encouraging realistic image generation and a sharp enhancement loss is further introduced for high-quality sharp image generation. We instantiate our Lab2Pix for the task of label-to-image in both unpaired (Lab2Pix-V1) and paired settings (Lab2Pix-V2). Extensive experiments conducted on various datasets demonstrate that our method significantly outperforms state-of-the-art methods quantitatively and qualitatively in both settings.
17 July 2023 in IEEE Transactions on Multimedia
Multimodal Conditional Image Synthesis(MCIS) aims to generate images according to different modalities input and their combination, which allows users to describe their requirements in complementary ways, e.g. segmentation for shapes and text for attributes. Despite satisfying results in MCIS, a non-trivial issue is neglected. Some modalities are fully optimized and dominate the generation, while other modalities are sub-optimized and fail to contribute their complementary information. We coin this phenomenon as Modality Bias. Our analysis reveals that generative models own greedy nature . Specifically, the modality that shares less semantic gap with the synthesized modality will be greedily incorporated and thus takes a larger proportion in synthesis. The main idea of previous works in Modality Bias is to punish the greedy nature, which hurts the performance of dominant modalities and impedes their contribution to multimodal synthesis. Instead, we propose to utilize the greedy nature by setting dominant modalities as guidance for sub-optimized modalities through coordinated feature space, named Coordinated Knowledge Mining. Afterwards, improved uni-modalities are aggregated by fusing coordinated features to further boost the performance of multimodal image synthesis, called Coordinated Knowledge Fusion. Extensive experiments prove that our method not only increases uni-modal performance by a large margin, but also promotes multimodal image synthesis by fully utilizing complementary information from different modalities.
4 November 2022 in IEEE Transactions on Multimedia
Manipulating visual attributes of an image through a natural language description, known as text-to-image attributes manipulation (T2AM), is a challenging task. However, existing approaches tend to search the whole image to manipulate the target instance indicated by a description, thus they often fail to locate and manipulate the accurate text-relevant regions, and even disturb the text-irrelevant contents, e.g. texture and background. Meanwhile, the model efficiency needs to be improved. To tackle the above issues, we introduce a novel yet simple GAN-based approach, namely Structuring Image for Manipulating (SIMGAN), to narrow down the optimization areas from external to internal. It consists of two major components: 1) External Structuring (ExST), a pretrained segmentation network, for recognizing and separating the target instances and background from an image; and 2) Internal Structuring (InST) for seeking out and editing the text-relevant attributes of the target instances based on the given description and masked hierarchical image representations from ExST. Specifically, the InST structures target instances from outline to detail by firstly drawing the sketch and colors underpainting of instances with an Outline-Oriented Structuring (OuST), and then enhancing the text-relevant attributes and elaborating on details with a Detail-Oriented Structuring (DeST). Extensive experiments on benchmark datasets demonstrate that our framework significantly outperforms state-of-the-art both quantitatively and qualitatively. Compared with the state-of-the-art method ManiGAN, our approach reduces the training time by 88%, while the inferring time is three times faster. In addition, our approach is easily extended to solve the instance-level image-to-image translation problem, and the results exhibit the versatility and effectiveness of our approach. We release our code in https://github.com/qikizh/SIMGAN .