The weld geometry is directly related to weld strength. The weld geometry by manual measurement may be inaccurate due to human errors. In this study, the image processing is proposed to measure the geometrical dimensions of bead-on-plate weld. The image noise of weld was smoothed by median filter. The boundary of fusion area was enhanced by histogram processing. The edge of deposit and fusion area is then obtained using Laplacian-Gaussian operator and zero crossing detection. The demonstrated example shows that the image processing can effectively and accurately measure the weld geometry.