For Individual Photos
1. Upload your original or edited image in Photoshop
2. Click File > Export then select Save for Web.
3. Change the image size according to your preference in the Image Size fields.
4. Click 2-Up. This enables you to see the original image on the left window and what the smaller file looks like on the right.
5. Tick sRGB so you’ll know that the colors displayed in the window are the actual colors that will be seen on the web page.
6. Click 4-Up. The top left window contains the original image. The other three windows show the image at Maximum Quality, High Quality, and Medium Quality based on the settings you set in Step 3. It is also possible to click on any of those three images so you can change settings.
7. The differences between the compressed images may be slight. To see those differences clearly, click the Magnifier Tool in the upper left menu. Clicking on an image will then magnify it. If you want to see a part of the magnified image that is not visible, click the Hand Tool and drag the image. Or you can press the spacebar and drag the image.
8. Clicking a compressed image also allows you to see several compression options, located at the upper right of the Save for Web window.
9. Tick the Optimize box to further reduce the size.
10. When you are satisfied with the compression, click Save. In the Save Optimized As window, enter a filename different from the original image filename. Choose whether you want to compress the image a JPG, GIF, or PNG file. JPG format allows you to select the percentage of compression. By choosing PNG or GIF formats, you can use Photoshop to manipulate colors and transparency during compression. Click Save.
11. Close the original file without saving.
For Batch Compression
1. Save all the photos you wish to compress in a folder.
2. Open Adobe Photoshop then click File > Scripts > Image Processor.
3. Click Select Folder under the Select the images to process.
4. A new folder will be automatically created in the original folder; this is where the compressed images will go. If you want to change the destination folder, tick Select Folder under Select Location to Save Processed Images. Navigate until you arrive at the destination folder of your preference.
5. In the same window under the File Type section, adjust the settings to reduce the size of your image file. Tick the Resize to Fit box and set the maximum height and width of your compressed photos.
6. Input a number between 1 and 12 in the Quality field. The higher the number, the bigger the file size.
7. Select Save as JPEG.
8. Images can be edited with a single action during export. Click Run Action to view actions available. Use the first column drop down to select the action group and the second drop down to pick your desired action.
9. After inputting all your settings, click Run. The images in your folder will be processed and saved to the specified destination folder.