  Recently, CLIP has found practical utility in the domain of pixel-level
zero-shot segmentation tasks. The present landscape features two-stage
methodologies beset by issues such as intricate pipelines and elevated
computational costs. While current one-stage approaches alleviate these
concerns and incorporate Visual Prompt Training (VPT) to uphold CLIP's
generalization capacity, they still fall short in fully harnessing CLIP's
potential for pixel-level unseen class demarcation and precise pixel
predictions. To further stimulate CLIP's zero-shot dense prediction capability,
we propose SPT-SEG, a one-stage approach that improves CLIP's adaptability from
image to pixel. Specifically, we initially introduce Spectral Prompt Tuning
(SPT), incorporating spectral prompts into the CLIP visual encoder's shallow
layers to capture structural intricacies of images, thereby enhancing
comprehension of unseen classes. Subsequently, we introduce the Spectral Guided
Decoder (SGD), utilizing both high and low-frequency information to steer the
network's spatial focus towards more prominent classification features,
enabling precise pixel-level prediction outcomes. Through extensive experiments
on two public datasets, we demonstrate the superiority of our method over
state-of-the-art approaches, performing well across all classes and
particularly excelling in handling unseen classes. Code is available
at:https://github.com/clearxu/SPT.
