Hello some info maybe of help
When preparing images for online distribution, it's useful to specify image size in terms of the pixel dimensions. Keep in mind that changing pixel dimensions affects not only the size of an image on-screen but also its image quality and its printed characteristics--either its printed dimensions or its image resolution. To change the pixel dimensions of an image in Photoshop
- To change the pixel dimensions of an image in photoshop
- Choose Image > Image Size.
- Make sure that Resample Image is selected, and choose an interpolation method.
To maintain the current proportions of pixel width to pixel height, select Constrain Proportions. This option automatically updates the width as you change the height, and vice versa. - Under Pixel Dimensions, enter values for Width and Height. To enter values as percentages of the current dimensions, choose Percent as the unit of measurement. The new file size for the image appears at the top of the Image Size dialog box, with the old file size in parentheses.
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