High-Speed Bitonal Display
With LEADTOOLS Document toolkits, you can improve the load and display performance of 1-bit (black and white) images that are commonly used for document storage and FAX transmission.
LEADTOOLS achieves this speed improvement by letting you load an image in its RLE-compressed format, where you can work with it as if it were a fully-expanded bitmap. This not only speeds the throughput and storage, but also speeds up the display of large images that are scaled to fit a window. The display improvement is achieved because, internally, it is no longer necessary to decompress all lines of data to display the scaled-down image.
You can also do the following to enhance the quality of 1-bit (black-and-white) image display:
§ Specify a scale-to-gray option, which increases the clarity of the 1-bit images when they are scaled (fit, zoomed in, or zoomed out).
§ Specify a favor-black option which prevents loss of details, such as fine lines, when an image is scaled down (zoomed out).
When receiving transferred data, as in an Internet application or a FAX modem transmission, you often want to display the image as it is received.
To meet that need, LEADTOOLS provides simple functions that let you load image data into a bitmap as it is received. You can also use the LEADTOOLS paint-while-load feature to display the bitmap as it is received.
For Internet support, LEADTOOLS provides a plug-in DLL that can be used on WIN32 systems to view compressed images with Netscape Navigator or Microsoft Internet Explorer.
Compensating for Fax image resolutions
When LEADTOOLS loads and displays an image, it assumes that the X and Y DPI are the same. However, Fax images commonly have a resolution of 200x100 to allow for faster transmission. This causes the image to appear stretched. There are two ways to resolve this, so that Fax images do not appear stretched. Both methods will display the image correctly, but one will modify the data permanently.
§ The SAVEFILEOPTION structure specifies extra options for writing an image file, including arguments that instruct LEADTOOLS to use actual image resolution for image display. This will allow the fax image to be displayed correctly without altering the image data.
or
§ Resize the image (using the relevant platform-specific function) to compensate for the difference in resolution. For example, if the image were 200x100 DPI, you would resize the image by doubling the height so that Y=200. This solution modifies the actual bitmap data. For more information, refer to topics under “Resize” and “Resizing Images” in the Raster Imaging help file index.
LEADTOOLS provides a "magnifying glass" that can be attached to a window handle. This magnifying glass provides a means of "zooming in" on the image loaded into the window to which it is attached.
LEADTOOLS also provides a "zoomed view" that can be attached to a bitmap window. This Zoom View provides a means of "zooming in" on the image loaded into the window to which it is attached. This is similar to having multiple Magnifying Glasses on the same source image.
Using TIFF IFDs to speed up file loading
TIFF files can contain large numbers of pages. This can make loading and saving these TIFF files very time consuming. Using an IFD (Image File Directory) speeds up loading, saving and getting information from very large TIFF files by allowing you to designate exactly where (on which page) to begin the load.