What format is the file in?

Make sure the file is in one of the raster formats that Scan2CAD supports. If it isn’t, do one of the following:

Convert the file to a supported format using an image editing program like Photoshop.

Scan the drawing again and save it in one of the supported raster file formats.

Scan the drawing directly into Scan2CAD using File Menu > Acquire.

Is the file a TIFF file?

Scan2CAD does not support tiled TIFF files.

Even if the TIFF file is a type that Scan2CAD supports you may get warning or error messages when you read it in. Click OK to pass these messages. The file will probably load successfully despite them.

If you do not want these messages to appear in future, unselect the File Menu > Raster > Options > TIFF Display Warnings option.

How large is the image?

In theory Scan2CAD will load any raster image up to 64,000 x 64,000 pixels in size for Windows XP and all later Operating System(OS) versions.

Windows OS versions earlier than Windows XP are restricted to 32,000 x 32,000 pixels in size. This equates approximately to a 13.3 foot x 13.3 foot or 4m x 4m drawing scanned at 200 dpi or a 6.6 foot x 6.6 foot or 2m x 2m drawing scanned at 400 dpi.

In practice the maximum image size that Scan2CAD will handle is determined by your PC’s system resources – for example the amount of physical and virtual RAM it has.

We recommend that you try to keep your raster images small to save disk space, resources and processing time. You can do this by:

Not scanning at an unnecessarily high resolution. 200 to 400 dpi is optimal for most images.

For example, if you scan an E or A0 size drawing with a color depth of 2 at a resolution of 300 dpi it will take up about 16Mb of memory.

If you scan it at a resolution of 600 dpi it will take up about 64Mb of memory.

(However, bear in mind that while you can decrease the resolution of an image after scanning, you cannot increase it. Therefore it can be better to err on the side of higher resolution.)

Using the lowest possible color depth.

For example, suppose you scan an E or A0 size drawing at a resolution of 300 dpi:

If you scan it with a color depth of 2 it will take up about 16Mb of memory.

If you scan it with a color depth of 256 it will take up about 128Mb of memory.

If you scan it with a color depth of 16.7 million it will take up about 385Mb of memory.

Note that a file that takes up very little space on your hard drive may be huge when loaded into Scan2CAD. This is because some raster file formats like TIFF can compress very large files to a very small save size. When these files are loaded into Scan2CAD they have to be uncompressed so that they can be processed. To see the uncompressed size of a raster image load it into Scan2CAD, go to File Menu > Raster > Statistics and look at the Size (bytes) figure.

“Raster image extent limits exceeded” message

If you are using a Windows OS version earlier than Windows XP, this message appears if you try to open an image that is larger than 32,000 pixels in either width or height

If you try to open an image that is larger than 32,000 pixels in either width or height Scan2CAD will break the image down into smaller “tiles”.

The message tells you how many “tiles” Scan2CAD will have to split the image up into in order to process it. For example, it may have to split the image into 4 columns by 2 rows (8 tiles). You need to open and convert each of these tiles separately and then join them back together in your CAD program after conversion.

We suggest the following procedure:

2.	Click to load tile 1,2 and convert it and save it as Tile2.Dxf.

Alternatively, try making the raster image smaller by rescanning the drawing at a lower resolution.