  Table structure recognition is an indispensable element for enabling machines
to comprehend tables. Its primary purpose is to identify the internal structure
of a table. Nevertheless, due to the complexity and diversity of their
structure and style, it is highly challenging to parse the tabular data into a
structured format that machines can comprehend. In this work, we adhere to the
principle of the split-and-merge based methods and propose an accurate table
structure recognizer, termed SEMv2 (SEM: Split, Embed and Merge). Unlike the
previous works in the ``split'' stage, we aim to address the table separation
line instance-level discrimination problem and introduce a table separation
line detection strategy based on conditional convolution. Specifically, we
design the ``split'' in a top-down manner that detects the table separation
line instance first and then dynamically predicts the table separation line
mask for each instance. The final table separation line shape can be accurately
obtained by processing the table separation line mask in a row-wise/column-wise
manner. To comprehensively evaluate the SEMv2, we also present a more
challenging dataset for table structure recognition, dubbed iFLYTAB, which
encompasses multiple style tables in various scenarios such as photos, scanned
documents, etc. Extensive experiments on publicly available datasets (e.g.
SciTSR, PubTabNet and iFLYTAB) demonstrate the efficacy of our proposed
approach. The code and iFLYTAB dataset are available at
https://github.com/ZZR8066/SEMv2.
