All sizes of digital photo images need to be "optimized" to improve web download time by increasing the amount of JPG compression in the image, but there is a distinct compression point where the image quality starts to significantly degrade and digital "artifacts" become noticeable to the human eye. These artifacts appear in the shape of square blocks of color or as stray pixels along the edges of the image, as seen in the examples below:
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| No JPG Compression image size = 31k |
30% JPG Compression image size = 20k |
70% JPG Compression image size = 17k |
| Click on photo images to see enlargements. | ||
Every digital photo has its own compression point where artifacts begin to become noticeable, so there is no specific rule as to the amount of compression that can be applied. Some photos can be compressed as much as 70%, while others cannot be compressed more than 30% because the artifacts begin to stand out and appear as defects in the image (a flower in the above example).
Also, the reduction in image size is not always significant enough to justify the excess compression, which can be seen by comparing the image size of the three examples above. The original image is 31k in size, and 11k of data is removed with just 30% compression. But only 3k more of data is removed when 70% compression is applied to the original image. Every photo used on a web page must be individually optimized for size, download time, and image quality.
Image enhancement of existing photos can remove scratches, backgrounds, etc. Any photo or negative can be scanned in, but the best results are always obtained using high-resolution digital photograph originals.
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| Before | After |
| Click on photo images to see enlargements. | |
Digital photos can be modified by "painting" out each individual pixel, but it is a very time-consuming and painstaking process. Above is an example of image enhancement for a photo taken on location in a greenhouse. The black background was picked up and then carefully "painted" in to remove all evidence of the greenhouse background. This was necessary because the plant is almost six feet across, so there was no way to provide a solid black background, but it took many, many hours of work to create the final image.
The "after" photo also has an example of a "mouse roll-over" effect.
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