Thursday, January 24, 2008

Output Levels

How many times do you receive memos or alerts that feature a photo as a prominent part of the message? Be on the look out for so and so. This car has been seen in the vicinity of ... Sometimes these alerts are printed on the office ink jet printer, sometimes they are printed on a laser printer, and they can be faxed as well.

What: we want to fine-tune our images to match our output device. We want to produce the best quality images that we can with the printers that we have around the office.

How: Output Levels
Images end up with clogged shadows or blown out highlights when printing to these devices because the device can't support levels above or below a certain point. This is where the Output Levels sliders come into play. We are going to take our normal 0 to 255 range and compress this to match the limitations of our device. (note: there will be some trial and error involved as you figure out the range of your output device)

In our image, the shadow detail will be lost when printing on my laser printer unless I do something to protect it. I can also protect what little highlights there are. In the Output Levels portion of the Levels dialog box, I can change the shadow value from 0 to an appropriate number - in this case 15. I can change the highlight value as well - from 255 to 235. I am forcing a reduction in range - and forcing the image into a range that my printer can handle.

This technique can also be valuable when preparing images for use in PowerPoint. Depending on the projector's capabilities, as well as the lighting in the room, you may need to fine tune your images in order to display them correctly.

Why: We focus on bringing out details in images that will be an important part of identifying individuals or objects. These details can get lost when printing to lower quality output devices or when using a fax or photocopy machine. Adjusting the Output Levels of the image allows us to correctly display or distribute these images within our enterprise.


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