Image degradation

I received an email from a client with questions regarding image degradation which requires an answer suitable for framing. The client (Hi Jean) has some head shots by a professional photographer which are printing in a manner not consistent with the screen images. Jean wonders if maybe there is some image degradation going on somewhere between her and the printer.

I touched on some of the issues here with a recent article cleverly titled a Jpegs and Jargon. the following from that article: It is ok to save a copy of a file as jpeg if it has been sized correctly for its final place on the web, however if you send a jpeg to a site for display and they decide they want it a bit larger or smaller it is like making a recording of a recording the quality deteriorates drastically.

jpeg artifacts distort the image after each save

jpegs are a final product for the web, not to be reworked

For printing we use a non compressed file such as a tiff or pict file. If Jean sent jpegs to the printer and they were resized by the printer we would have image degradation.

The jpeg format is considered a lossy format, meaning some areas are fudged to keep the file size small. In an oversimplification Its as if we were painting a blue sky and just used a roller and one color.

I dont think that is the issue here as Jeans problem is one of color shifting.

If you have ever walked through a department store tv display you may have seen noticed how even in ideal settings with trained sales people the tvs while on the same channel have varying degrees of color shifting. Some folk like a lot of color in their tv. Some like the color washed out. And some like green skin. Computer monitors are little tvs. They can be viewing the same image and look different according to settings of the user, manufacturer, model, type of monitor, even room lighting.

So Jean has a lovely picture ready to be printed, looks great on her screen, sends it to the printer, they pull it up and then print it to match what it looks like on their screen.

Another issue is rgb versus cymk. The computer monitor uses three colors, Red Green and Blue. rgb. Printers use four, Cyan Yellow, Magenta, and Black. cymk When a file is converted from rgb to cymk the software doing the converting has to decide how to distribute colors.

Another issue is that the monitor is illuminated, the printed surface uses only reflected light from the room. Sunlight, incandescent bulbs, curly bulbs, fluorescent, lcds and a mix of all of these.

So I am thinking the problem here isnt so much image degradation but image interpretation.

Proposed Solution: I would manipulate the non-compresed image (not the jpeg, make sure always to get the raw image or other non compressed format from the photographer not just jpegs) until I could print a version of it on my home printer that I was happy with then send that print along with the non-compressed image to the printer for him to work toward.

Non Compressed images are generally too large to be emailed. You will have to upload or burn to a disk or send them a thumb drive. A lot of printers have upload facilities with their own set of requirements. If their requirements are cymk and you have rgb you will have your own opportunity to adjust the image in photoshop and even print out at home.

If the photographer sends non compressed tiffs or photoshop files that is good because you can resize copies and make jpegs from those. Jpegs are the final image made for the web and should not be resized or altered in any way as you will suffer from the dreaded image degradation. Be sure to read a Jpegs and Jargon to get an idea of file size for printing.

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