It's always a good idea to create a backup of your original image file before making changes to its size. This will allow you to revert to the original in case something goes wrong or you don't like the end result. Select the image file, press ⌘ Command+C, and then press ⌘ Command+V to make a copy in the same location. Usually this will open by default when you double-click the file. If the image opens in something else, you can right-click the file and select "Open With" and then "Preview." This will open a new window that will allow you to resize the image. You can select "Pixels," "Percentage," and several other units to scale the image by. Selecting "Pixels" will allow you to determine the exact size of the resized image. The two fields are linked, and changing one will change the other to keep the image proportions correct. This will prevent stretching or squishing of the image. If you want to freely resize both fields, uncheck "Scale proportionally" to unlink the two. You'll be able to see what the new file size will be at the bottom of the window before you apply your changes. This is useful if you're resizing the image to fit the file size limitations of email or other online services. The image will be resized according to the settings you entered. If you aren't happy with the results, press ⌘ Command+Z to undo the changes and revert to the original size. If you are happy with the new size, you can save your changes to the file. Click the "File" menu and select "save" to save your changes.

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Write a summary of the previous text in Hindi:
इमेज फाइल की एक कॉपी बनाएँ: प्रीव्यू एप्लिकेशन में इमेज को ओपन करें: टूल्स मेनू पर क्लिक करें और "Adjust Size" सेलेक्ट करें: जिन यूनिट्स को आप उपयोग करना चाहते हैं, उन्हें सेलेक्ट करने के लिए ड्रॉप-डाउन मेनू पर क्लिक करें: आप इमेज को जैसा चाहते हैं उसकी नई चौड़ाई या ऊँचाई डालें: नयी फाइल का साइज़ चेक करें: बदलावों को एप्लाई करने के लिए "Ok" पर क्लिक करें: अपनी फाइल को सेव करें: