Photoshop does a poor job when it comes to jpeg sizes. They have a 1 to 12 scale, while most other programs have a 1 to 100 scale. If you use PS to save an image in jpeg format, a 9 is the best number to use. Anything over that will just make a bigger filesize, but won't result in a better image. If you save the image with a setting of 12, then compare it to a setting of 9....there will be no visible difference.
There is a reason for this. The better way to save a jpeg is with a program that uses the 1 to 100 jpeg settings. With a program like that, I use a setting of 85. This is called the "Q" or quality. This is derived from the five factors of an image.....the red, blue, green, chrominance, and luminance of the picture. When you save a jpeg, you are compressing the image. That means that you are throwing away some of the information in the picture.
You can eliminate the chrominance and the luminance, since they are a product of the brightness of the colors in the picture. The chrominance and luminance make up 20% of the picture, so if you eliminate that, you are left with 80% of the information in the picture. To play it safe, I add an extra 5% of the information, making it 85% or a quality of 85. Anything over that will not be visible in the picture. Saving it at a 12 in Photoshop will not yield any benefits over saving it as a 9.
I agree that using the descreen function will result in a softer picture, but you can regain that sharpness in PS by using the unsharpen mask. If you don't use the descreen function, you will get moire, and that is hard to eliminate.
I also use a black background to eliminate the bleed through that you find in some magazines. I use a black foam board, but any black paper or cardboard will work.
I appreciate the tips ellias. All input is welcome.
