Archive for the ‘Uncategorized’ Category

Fixing Photo Color Casts and Contrast

November 4, 2014

Before and after restoration of a faded old photo. Notice in the top histogram, the peaks of the red, green, and blue channels aren’t lined up and don’t reach to the left and right edges. That results in a color cast and reduced contrast. If you have software that has individual R,G,B levels or curves controls, it’s pretty simple to fix, and followed by fine-tuning of exposure looks like the bottom picture. I’ve used both Lightroom and Photoshop Elements to fix hundreds of old photos like this. In Lightroom, it’s “Edit Point Curve” in the Tone Curve section. In Photoshop Elements, a Levels Adjustment Layer. Photoshop has a Curves Adjustment Layer as well, which is more flexible but can be harder to use.

I start by moving the endpoints of all three channels to the edges, maximizing the contrast and luminosity range. If the results still have a color cast (often not the original one), I move midpoints until it looks the way I want. Sometimes I fine-tune it afterward with conventional white-balance controls (color temperature and tint).

Histogram+levels demo

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Electronic Image Destabilizing

January 21, 2010

Do you understand all the automatic settings on your electronic equipment? Recently, I was reminded to not assume that the current settings are appropriate, when one of them did the opposite of what it was supposed to.

I was shooting video of a mini-conference in which a lot of the footage was of one person at a time standing and speaking behind a podium, in front of a white board. The camera was a Panasonic consumer MiniDV camcorder that was bought several years ago on a budget (it wasn’t mine). I was using a tripod and did a lot of head-to-waist shots with occasional zooms or pans when the speaker got close to the edge of the frame.

Fairly often, the shot would jerk somewhat up and down again, as if the tripod head were loose and shaking. It was a consumer-level video tripod (a Velbon), but I thought I had tightened the pan/tilt head about right to prevent slipping. I fiddled with it a few times, then started looking through the camera’s setup menus. There was an icon on the LCD that said “EIS”, so I looked up what that meant, since I understood all the other information on the screen.

I found out that “EIS” means Electronic Image Stabilizer. With it on, the camera analyzes the image and when it detects something moving up and down rapidly, it concludes that there is camera shake occurring, so it shifts the image in the other direction to compensate. It’s a poor man’s Steadicam for hand-held shots.

But the EIS backfired on my tripod-mounted shots. Whenever one of the speakers would wave his arms up and down to emphasize a point, the camera would lock on to the arms and try to keep them stationary, moving the podium and white board up and down instead! So it destabilized my stable shots.

I turned off the EIS, and my shots were stable for the rest of the event.

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