Adobe Photoshop has the ability to resize images. You can reduce the picture without any problems - its quality hardly suffers. Increasing the size is much more difficult. You will have to process a highly enlarged image to make it look more or less decent.
Instructions
Step 1
If you want to zoom in on the picture when processing small details, select the Zoom Tool from the toolbar. The same effect is achieved by using the hotkeys Ctrl + "+". To zoom out the image, use the "Magnifier" while holding Alt on the keyboard, or use Ctrl + "-".
Step 2
To enlarge the picture, select the Free Transform command from the Edit menu or press Ctrl + T. Move the cursor over one of the control knots, hook it with the mouse and pull it to the side. Depending on the direction of movement, the image will increase in width or height. To resize evenly, hold down Shift on your keyboard.
Step 3
There is another way. From the Image menu, choose Image Size. Enter a new size in the Width and Height boxes under Pixel Dimensions or Document Size. Keep in mind that the more you increase the value, the more distortion will be in the final document. Color noise, blurred areas, artifacts, etc. may appear.
Step 4
When the picture is enlarged by 10%, there are practically no distortions. Therefore, you can change the size in stages, increasing the image at each step within these limits. In the Document Size section in the right pane, expand the list and select percent. Check the Constrain Proportions checkbox so that the picture changes proportionally.
Step 5
The height and width will be set to 100%. Enter 110 in any box to enlarge the picture by 10% and click OK. Repeat this procedure until the picture is enlarged to the required size.
Step 6
Of course, even with this method, the image quality suffers. You can sharpen it. Duplicate the layer Ctrl + J and in the menu Filter ("Filter" in the group "Other") select High Pass ("Color contrast"). Set a small radius so that the image appears slightly through the gray film. Apply the Overlay blending mode to the layer.
