About image compression
Image compression is a technique used for storing a visual image that reduces the amount of digitized information needed to store the image electronically. When you save a document in either Microsoft Document Imaging Format (MDI) or Tagged Image File Format (TIFF), image compression is used to reduce the size of the file.
The MDI format uses an improved image compression technology that results in smaller file size, and better image fidelity than the TIFF format.
Change the image compression options when you save a document
- On the File menu, click Save As.
- In the Save As dialog box, click Options.
- Select the options you want on the Compression tab.
Change the image compression options when you scan a document
- Select the preset you want to use in the Scan New Document dialog box.
- Click Preset options, and then click Edit selected preset.
- In the Preset Options dialog box, click the General tab, and then click Advanced.
- Select the options you want in the Advanced Scan Settings dialog box.
When you use the Options dialog box (Compression tab) or the Advanced Scan Settings dialog box to change the compression options, you can choose to optimize the compression either in favor of file size or image quality. Saving a document to achieve a smaller file size will result in more image loss; saving a document for better image quality results in a larger file size. The optimal setting depends on how you intend to use the image.
What happens when you change compression options?
When you select a different compression option, the pages in a document are compressed using the new option under the following conditions:
- you save the document with a different file format or file extension (all of the pages in the document are saved with the new compression option)
- you make annotations a permanent part of the document (any page with an annotation will be saved with the new compression option)
- you make changes to a page (any page that you make changes to is saved with the new compression option)
So, when you save a file with a different compression option (without changing the file format), only pages that you have made changes to are saved with the new compression option. To compress all the pages with a new compression option, you must make changes to each page. For example, rotate all the pages in a document 90° right, then 90° left to make sure that each page is marked as changed, but without actually making any visible changes to your document.
The following table shows the type of image compression used for each of the image types you can create in Office Document Imaging.
| Image type | Compression format used |
|---|---|
| Monochrome TIFF | TIFF CCITT Group 4 FAX |
| Grayscale TIFF | TIFF 6.0 JPEG |
| Color TIFF | TIFF 6.0 JPEG |
| Monochrome MDI | MODI BW |
| Color MDI | MODI Color |
| Grayscale MDI | MODI Color |