The Picture Format tab appears on the ribbon. In most cases, you won't need the resolution to be higher than that. In the Default resolution list, select a resolution of 150ppi or lower. Make sure that Do not compress images in file is not selected. Note that if you discard the editing data, you won't be able to restore the image. This option removes stored data that's used to restore the image to its original state after it's been edited. Under Image Size and Quality, do the following: Removing unused data will reduce your file size. The more data points you have in your workbook, the larger your file size will be. If you have worksheets with data that you're not using-and that don't contain any formulas you're using-delete them from the spreadsheet. In the Save as type list, select Excel Binary Workbook (*.xlsb). If you want to keep the default to Excel Workbook (.xlsx) but save the current file as binary, select the option in the Save As dialog box: This option sets binary format as the default. Under Save workbooks, in the Save files in this format list, select Excel Binary Workbook.

However, for most purposes, the binary format is sufficient and saves to a smaller file. The default format is XML based, which is important if you're using your data with third-party programs because XML is an open standard. You can reduce your file size by saving your spreadsheet as a binary workbook (.xslb) instead of the default format (.xslx). Save your spreadsheet in binary (.xslb) format

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