POTW #10: The Fattest Squirrel I've Ever Seen

shutter speed: 1/30 sec, focal length: 72 mm (432 mm in 35 mm equivalence), aperture: f/3.5, distance: about 2 meters

I took this picture on my honeymoon in Havre de Grace, Maryland. The squirrels on this boardwalk were not at all afraid of humans, and it shows. I would not be surprised if this guy had been hand fed a few happy meals this year.

A little bit about the GIMP processing on this file:
On my first POTW post (also of a squirrel), I included some comments about removing purple fringing from high contrast areas in the photo. I thought I'd give a little explanation of the more basic steps I used on this photo. These are pretty simple techniques that can make a lot of pictures look sharper and more contrasty. This picture just happened to look particularly abysmal to me before processing. So I thought it would be a good example.

1. Levels: I just hit the auto button in the levels tool in GIMP. Unless it's a very strange photo, the auto button usually gives results that I'm pretty happy with.

2. Curves: I just drag the curve down a little bit at the first quartile mark and up a little bit at the third quartile mark to make it slightly S-shaped. This increases contrast in the mid-tones of the image (while lowering contrast in the high lights and shadows.

3. HIRALOAM: This is a special use of the unsharp mask filter; it stands for HI RAdius LOw AMount. In this case I used a radius of 50 pixels (about 7% of the image width), with an amount of 0.12 (threshold=0). I don't do this to pictures that often. Its purpose is not to sharpen in the way unsharp mask usually does. Instead it provides a subtle contrast enhancement. I like the effect, but it's the most computationally intensive thing I did to this photo and probably has the least effect on the final appearance.

4. Unsharp Mask: This increases the appearance of sharpness of the image. Using a tripod would increase the actual sharpness. Unfortunately unsharp mask sharpens everything including noise. I used a radius of 2 pixels and an amount around 80% (threshold =0).

Here's an animated GIF showing the evolution:


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5 thoughts on “POTW #10: The Fattest Squirrel I've Ever Seen”

  1. Ok, one point of debate and one interesting anecdote:

    1. I think that, in general, "auto levels" go too far. Typically it cuts off the the top 5% and bottom 5% of the existing brightness range and then remaps what's left to the full 0-256 range. Obviously it works, but any pixels in the brightness range that got clipped will be rendered as pure white or black and will therefore lose any detail that they had. I think this is what happened to the white parts on the squirrel's hips. So, if you use levels, I think it's better to manually select the region that you want to keep to prevent clipping.

    However, since you're making a curves adjustment, I don't think there's any reason to use levels at all. Both of the tools do the same thing remapping the brightness distribution of the image from the original to what you finally want. In fact, levels is basically just a simplified way to do curves without the complexity (or control). From the curves window, you can change the input range of brightnesses on the x-axis (which is what you did in levels as a separate step before) and then also change the contrast using the curves. Doing this as one step instead of two reduces the risks of posterizing the image and lets you keep all of the image information.

    The interesting anecdote is that using an S-shaped curve in curves basically replicates the exactly look of conventional b&w film. Films like Tri-X are/were famous for having long flat wings in their sensitivity curves at the bright and faint end. Kodak made it that way because pictures please the eye with that sort of contrast and that hasn't changed in digital.

  2. Excellent. I didn't actually think anyone would read this post and then decide to go learn to use GIMP, but I did hope that by posting what I did I would learn a few things from the master. I'll try not using levels and see if I can retain the information in the squirrel hip region. Thanks.

  3. I don't know enough about photography to appreciate the image processing and such you've done here, other to say I agree it looks better in the end than the beginning. That being said...

    I LOVE THE SQUIRELL!!!!!!!!!!!!!!! it's fat, and squishy looking. i want to take it home and feed it cupcakes and poke it in the belly 🙂

    thanks for the pic, it's lovey.

  4. I'm with Jenn on this one, pretty much 100%.

    Squishy squirrels are probably the best kind of squirrels to have. Plus, they're great for taking care of leftovers. 😀

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