I only see a few blips, in my converted tiff to GDSII file. What's wrong?

My guess is that you need to adjust the Image Import Option called "Gray Scale Percentage (%)"; this feature allows you to let ACE know which pixels to import and which pixels to ignore. Try using a different percentage like "10".   Sample image:

http://www.numericalinnovations.com/help/ace_0515.jpg

Note: Also, when you're in the CAD viewer, set the Level of Detail to "All", so you can see all small pixels being drawn. Sample image:

http://www.numericalinnovations.com/help/ace_0515a.jpg

Note: Also, please make sure you have selected the correct pixel units for your tiff images (like 1200 dpi, or 1 micron per pixel).