Open the digital camera photo you want to resize and turn on the ruler (Ctrl+R).
Open the Image Size dialog box from the Image menu (Ctrl+Alt+I). Note that there are two sizes here. The top pixel size defaults to the pixel size of the photo, and the middle document size is the actual physical size of the photo. The resolution is 72 ppi is suitable for monitor output but not suitable for printing.
Let's first understand the most important part of this dialog box, resizing the image pixels. Let's do an experiment and enter 144 (2 times 72) in the resolution field. Note that there is no change in the physical size of the photo at the document size, but The pixel size of the pixel size part of the photo becomes twice the original size. The reason here is that ppi (pixels per inch) represents the number of pixels per inch. The operation here is equivalent to us keeping the physical size of the photo unchanged, and then increasing the number of pixels per inch. The number of pixels in the inch is twice the original, so the number of pixels in the width or height of the photo becomes twice the original. Why do the pixels need to be increased? Because we turned on resetting image pixels. So why don't we Can you use the repixel feature to increase the resolution of a photo while maintaining its size? The answer is No. Because repixeling makes a low-resolution image (72 ppi) soft, blurry, and pixelated.
Now, let's see what happens if we turn off repixeling the image. First we restore the previous settings, hold down the Alt key, then the Cancel key will change to the Reset key, click Reset.
