Introduction

TiffExtract is a simple program that uses QISLIB to open a GDSII file and extract the data in a small window and convert it into a monochrome bitmap. This is a useful function for inspection equipment -- the bitmaps are often used for defect detection.

The purpose of TiffExtract is primarily educational - it is intended to help a programmer who plans to use QISLIB get up to speed quickly. We provide a complete source project for TiffExtract and a binary that a programmer can use to excercise QISLIB. For high performance applications a one would prefer NexgenRIP which has a 2nd generation multi-threaded rasterizer built in.

Links

TiffExtract GUI

Source Code Annotation

Processing Very Large Files

Opening a GDSII File

In order to open a GDSII and process one or more layers the client (TiffExtract) program needs to:

• Initialize QISLIB
• Define settings for QISLIB (before opening the GDSII file)
• pass QISLIB the filename to open
• pass QISLIB to structure name to open
• pass QISLIB the list of layers to turn on (or off)

Selecting the Window and Producing a Bitmap

• pass QISLIB a geometric window that you want to process
• pass QISLIB a command to extract a bitmap to disk

The flow chart below shows the important function calls that must be made prior to opening the GDSII file.

Once the GDSII file is opened then the correct structure should be opened and the layer(s) of interest set to ON.

Now we can define a window of interest and instruct QISLIB to rasterize that window into a TIFF file and write the file to disk. These two steps can be put into a loop and hundreds or thousands of windows extracted.

When we are done extracting windows, the calling application should close QISLIB. This releases the memory (which could be quite a lot!) and also releases the license.