ACC1x: Bitmap May Not Be Displayed Correctly

• Microsoft Access versions 1.0, 1.1

SYMPTOMS

A bitmap that is displayed correctly in another application is not displayed correctly in Microsoft Access.

CAUSE

When Microsoft Access starts, it loads a fixed 256-color palette. This palette supports the most common colors used in bitmaps and metafiles. All pictures and OLE Objects displayed in Microsoft Access are mapped to this palette.

STATUS

This behavior is by design.

MORE INFORMATION

By using a fixed palette, Microsoft Access can display multiple pictures and OLE Objects on the screen at one time without each new object affecting the screen colors.

However, Microsoft Access can display multiple bitmaps at one time. Therefore, because Windows can use only one palette at a time, Microsoft Access uses a palette that usually is common to all the bitmaps Microsoft Access might display.

That is why bitmaps and metafiles displayed in Microsoft Access may appear to have a different color than when they are displayed in the application in which they were created. Because Windows can use only one palette at a time, each object Microsoft Access displays must be mapped to the fixed color palette loaded by Microsoft Access. Microsoft Windows determines this mapping. You cannot modify it.

Steps To Reproduce Behavior

1. Start Microsoft Paintbrush (PBRUSH.EXE).

2. Choose Image Attributes and select Black And White under the Color option.

3. Create a simple picture using several different shades of gray.

4. Choose Save from the File menu.

5. Under the Save File As Type option, select 256 Color Bitmap.

6. Start Microsoft Access, and open the sample database NWIND.MDB.

7. Open the Categories form in Form view.

8. Select the Picture Control.

9. Choose Insert Object from the Edit menu, and click the File button.

10. Choose the file you just created in Microsoft Paintbrush, and click the OK button. Note that the file loads as a solid black picture. Microsoft Paintbrush uses a custom palette to offer a variety of shades of gray. But Microsoft Access does not have the ability to load or reproduce this custom color palette. Therefore, it requests that Windows map each of the colors in the bitmap to the custom palette that was loaded when Microsoft Access started.