Preparing photos for the web
When posting an image online, you’ll shrink it and reduce the level of detail. The former makes details harder to discern while the latter smudges similar tones so that it has to account for fewer changes in the image. The results? Smaller files that download quickly and use less disk space.
Counter these effects by boosting your shots’ sharpness, contrast and detail using the sliders in iPhoto, Aperture and iPhoto. Increase the detail in Photoshop and other layers-based image editing apps by duplicating the image on a new layer above the original and applying the High Pass filter. Set the blend mode to hard light and use the opacity control to temper its strength. Crop your image to remove any surplus areas ( C in Photoshop); if you know what size it will be displayed, use the resize dialog ( ç+I in PS) to reduce its dimensions. Finally, use your image editor’s Save for Web feature to reduce the file size, keeping a close eye for any noise and degradation.