Thanks for visiting!
I’ve created this forum as a space for PhotoShop and retouching conversations in general. It would be great if it attracts questions from professional photographers, students, other graphic artists etc. I’ve worked with attorneys, doctors and other professionals who regularly use the program. For a little background about me and my work please visit my site: www.stevemauer.com. I’ve been working with the software since long-before-layers (okay, 1990), I’ve taught PhotoShop as at Seattle Central Community College, Cornish College of the Arts and for numerous private clients. I’m looking for the trickier questions though I will endeavor to answer anything I can. If I just launch into technical stuff like the benefits of curves-versus-levels in different color spaces I don’t think this will work very well. That said I intend to regularly feature tips, tricks and techniques with a bias towards print quality work. The main difference between print and Web being resolution. Let’s start there! Again, the goal here is an organic forum. I’m not working from an outline.
Resolution 101
Resolution is basically the amount of information in the image (pixels and their bit depth) compared to how the image will be displayed (internet, TV) or printed (lines-per-inch). Typical, up-close print quality resolution is 300 pixels-per-inch, 72 pixels-per-inch works for the Internet. Your printer might say DPI or dots-per-inch but if we’re talking resolution, we’re talking about pixels. In that case DPI means PPI. Pixel is a word used to describe the smallest discernible “dot” in an image. In an oil painting it’s a brush-stroke. In a 24 bit digital image it is one tiny piece of an image w/ about 16,700,000 different possible colors. The word pixel means “picture element.” Most print shops use/require a ratio of 2:1 resolution to LPI or better said, “Pixels-per-inch to Lines-per-inch.” Lines being the frequency of dots printed on the page. Newspapers are coarse, typically 85lpi. Hi-end magazines are 150lpi minimum and often 175lpi or more, hence the almost photographic appearance of their printed images. I don’t think it caught on very well but waterless printing presses are capable of printing 300 lines per inch or more. Indistinguishable from a photograph w/o a loupe. I worked on proof testing with AGFA back in the early 90′s. Storage was oppressively expensive, over $1/megabye. RAM was over $30/mb and people bought it. Just for the sake of shock and awe, a 16mb chip for a Mac Quadra 840 cost $700. I digress. Our tests determined a ratio of 1.414 to 1 offered the same quality as the then upheld 2:1 ratio. The tests saved a lot of people a lot of money.
Any PhotoShop questions, comments you have are appreciated!
Steve Mauer
steve@stevemauer.com
Tags: -fashion, -glamor, CMYK, color correction, PhotoShop help, product retouching, retouching
February 5, 2010 at 2:47 am |
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