The PNG image format is not as popular and widely supported as the JPEG format, so you may need to convert your PNG images to JPEGs before uploading them to services that don't support the PNG format. In Windows 8.1, both Windows Photo Gallery and Microsoft Paint can convert between the two formats. Other programs, such as Adobe Photoshop, Adobe Fireworks and Corel PaintShop Pro, can convert PNGs to JPEGs; however, these programs are fairly expensive.
Press Windows-X to display the Power User menu and click File Explorer to launch the utility. Select the folder that contains the PNG file, right-click the file, select Open With and click Paint to open the image in Microsoft Paint.
Click File, mouse over Save As and click JPEG Picture to display the Save As dialog.
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Select the destination folder from the left pane, type a name for the JPEG image into the File Name field and then click the Save button to convert the PNG to a JPEG.
Windows Photo Gallery
Launch Windows Photo Gallery, click File and select Include Folder from the menu to display the Pictures Library Locations dialog. To view images in specific folders, you must add the folders to the Photo Gallery library.
Click Add and select the folder that contains the PNG image. Click OK to add the folder to the library in Photo Gallery. All images in the folder are loaded automatically and displayed in the right pane.
Select the folder that contains the PNG image and then double-click the image in the right pane to switch to editing mode.
Click the Make a Copy button in the Manage group on the Edit pane to display the Make a Copy dialog.
Select JPG from the Save As Type drop-down box to save the image in JPEG format. Type a name for the image into the File Name field, select the destination folder and click Save to generate a JPEG image from the original PNG.