Open a photo in photo editing software such as Adobe Photoshop, Corel PaintShop Pro or a free online photo editing tool. Websites such as Piccy Fix and Photoshop Express allow users to edit photos online without purchasing software. It is recommended to use a test photo until you get the hang of editing to ensure the original is not damaged.
Digital images are made up of millions of pixels -- small squares of information that make up the photo. If you make a photo large enough on a computer screen, the tiny squares, which look like a series of tiles, are visible. Pixels are a unit of measurement for digital photographs, and while the number of pixels in an image can vary widely, the size of a pixel itself can't be altered. An 8MP camera, for example, takes photos that contain 8 million pixels per image. Many home computer users wish to reduce the number of pixels in an image for use online for emails and for publishing to social networking websites.
Navigate to the image menu in the photo editing software and select “Image Size.” For online applications, select the “resize” option.
Change the numbers in the “pixel dimensions” box to dictate what size the photo should be. Keep the small lock next to the numbers locked, or click the “constrain proportions” or “lock aspect ration” button so that the photo proportions are not altered, which can lead to a distorted photograph.
Size the photo based on your needs. Some websites and email providers have maximum allowable file sizes for uploading. Twitter, for example, has photo size and shape requirements and will not allow profile photos larger than 700 kilobytes. Click “OK” to accept the changes. The more pixels a photo has, the larger the image size will be.
Save the photo with the new pixel size using the “Save” or “Save As” function. Save the photo in a compatible format, such as jpeg.
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