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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.

tiff extract calls qislib and passes it a number of arguments. The result is a small tiff bitmap

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

Once this is done the next step would be to:
  • 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.

function_call_flow1.gif

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

function_call_flow2.gif

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.

function_call_flow3.gif

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.

function_call_flow4.gif