A Picked Fungus Flipped Over

• LBJ's

• Colour balance
• jpeg compression

Stereo formats

• A flipping mushroom reveals its spore-producing gills.

Pholota adiposa

This pretty mushroom was growing on a tree at head height, and so I missed seeing it. While wandering in the bush, I was studying the ground where most fungi grow and stopped to reluctantly photograph an "LBJ". The "Little Brown Job" was just like other LBJ's and impossible to identify without microscopy, but Murphy's Bush was revealing little else that day. I stood up to stretch my cramped limbs, since taking 3D photographs while crouched on the ground is not comfortable for old, arthritic, men and saw this beauty on a dead tree limb.

Colour Balance

Note how the colour of the two pictures above is different. Getting the colour right is a challenge in fungus photography. No matter how much care is taken, I have no control over your computer screen, especially if it is not running with "millions of colours" on the video card. But the problem above is more basic;

• the left hand picture uses jpeg compression with millions of colours,
• while an animated gif is on the right.

A gif provides simple motion but has a limited colour range of 256 shades. Even 256 shades makes a big file, especially if two versions are built in, as here. So this picture uses only 32 shades to take less time traveling down your 'phone line. (Most of my audience do not have "broad band" internet).

The gill colour on the animated picture is wrong, but it so happens it is pretty accurate for the colour of the spores, which dropped from these gills onto a piece of white paper (called a "spore print").

The jpeg version is as close to true colour as I could get. This involved measuring the colour of the light in the bush by photographing a white card. The digital camera may use this to correct the colour balance. The white card picture also works in Photoshop to correct colour balance (using the middle eye-dropper in "levels"). The camera and the software agreed: the camera recorded jpeg was the correct colour.

Problems with jpeg compression

1. Jpeg compression can change colours.
   To avoid this I increase the compression during post-processing in Image Ready until the colour starts to change, then stop.
2. Compression reduces the resolution of the image.
   In an ordinary picture on the internet you hardly notice it, but 3D information comes from slight differences between the two pictures. The tighter the compression, the worse the stereoscopic effect becomes. Stereo pairs on this web site are often on the verge of breaking down and so will not print well, because a printer has much better resolution than a computer screen. If you want to make Holmes cards, you will need the original images.
3. Anaglyphs have a particular problem with jpeg compression.
   They use red/cyan filters to separate the right from left eye information. If the colour of the anaglyph changes due to compression, serious cross-talk develops between the two channels and the stereo effect may fail completely. Anaglyphs can be used for big pictures and when that is combined with minimal jpeg compression, the file size gets rather large.

Identification

I e-mailed the picture to Clive Shirley, convinced I had found a honey mushroom but the reply came back that honey mushrooms have white spores, not brown and this was Pholota adiposa aff.

The "aff" term is short for; "has an affinity with a species recorded in foreign books but has not been officially described from New Zealand." It seems Pholota adiposa is quite common on dead trees around here and so aff is a piece of mycological political correctness! No worries, P. adiposa makes a pretty 3D subject no matter what it is called.

Parallel eye stereo.
Usually needs a stereoscope for computer monitor size images, but if your screen is 1024 pixels wide or more, free stereoscopic vision is usually possible.

Cross eye stereo.
Free stereo vision: no stereoscope needed.
These low pixel images are better on an 800 pixel screen for maximum 3D effect. However, not a wide-screen monitor, which distorts the images when set on 800 pixels and may make the stereo parallax too big.

Wobble stereo
Anybody can see it, but the 3D impression is poor.

Anaglyphs need red/cyan glasses.

Everybody who is not colour blind can see anaglyphs, as long as the goggles are good. Unfortunately the image colour is only satisfactory for blue and green, anything needing red is poor (which includes yellow).