Data watermark is of the surmount importance for data trading. Most of the data in the current data trading market is stored in the form of spreadsheets, yet there are few watermarking schemes specifically designed for tables. We propose a bitmap-based watermark scheme for table data. Our approach involves converting the table into a bitmap representation and utilizing classical image processing algorithms to embed a watermark that incorporates error correction codes. The watermarked data is then returned to its corresponding positions in the table. During the table conversion process, we apply the principle of minimal modification to minimize the impact of watermark embedding on the table data. Experimental evaluations demonstrate the effectiveness of the proposed scheme in preserving data integrity and accurately extracting watermarks.