The process in Photoshop starts with the rendered image just of the winks. The “glow” expands the image by 1.2× — the PovRay source allows for this extra space if an 11.03° viewing angle is used, but an angle of 9.2° is a “tight fit” and the image will need to be expanded correspondingly. Most images use a square aspect ratio, although the larger ones for desktop backdrop use have a more precise 8:7 ratio of width to height; those designed to have a glow added retrospectively are sized expecting this 1.2 factor to be applied. The process to add a glow to a rendered PNG in PhotoShop is:

• Expand the image by a factor of 1.2 if necessary.
• Convert to 16-bit mode.
• If generating a “light” version, apply a gamma of 1.5 in the “levels” dialogue.
• Duplicate the initial layer to what we’ll call layer 2.
• Create a layer mask for layer 2 from its transparency.
• Temporarily disable layer 2’s layer mask.
• Select the colour part of layer 2.
• Fill layer 2 entirely with Cambridge Blue (RGB(163,193,173)).
• Re-enable layer 2’s layer mask.
• To the layer mask, apply a Gaussian blur of radius 1/20 the unexpanded image width (or 1/24 of the width if the image was already expanded).
• Adjust the levels of the layer mask to 5 at the low end and 128 at the high end, with a gamma of 2.00.
• Move layer 2 below layer 1.
• Merge layer 2 and layer 1.
• Convert back to 8-bit mode.
• If necessary, assign the sRGB profile to the image.
• The naming convention used here is a “G” suffix for images with “glow" and “GL” for “glow, lightened".

The grey version of the image uses the same process but converts to 16-bit “Grayscale” mode, and uses the default interpretation of Cambridge Blue in that mode. The image is converted back to RGB before saving.

Alternatives are available in a range of smallish resolutions:

Glow as part of the image, lighter

The default colours are a little dark on a light background as it’s self-shadowing.

Lightened versions the square renditions exist that are suited for lighter backgrounds where adaptation makes the default colours look dark; the web site uses these lighter versions for the navigation when not in “dark mode” — on a dark background the lightened versions look washed out.

4800×4800 (7.9MB)
WebP (5.8MB)

Alternatives are available in a range of smallish resolutions:

Glow as part of the image, monochrome

The varying colours can map strangley to a monochrome representation; here therefore is a version with the winks a uniform grey colour.

4800×4800 (5MB)
WebP (3.1MB)

Glow as part of the image, half-toned

Some places one might want to reproduce the logo use processes that may be incompatible with transparency — notably on T-shirts, drinking receptacles, etc. The following versions are variants of the 4800×4800 image with the glow effect reproduced as a half-tone pattern, which should work better in these situations (the fine half-tone for larger reproductions, the coarse half-tone for smaller ones). The assumption is that high resolution is suitable for print jobs, so smaller versions are not provided.

Glow as post-process

In some cases for web use, it can be more helpful to apply the glow as a CSS post-process effect; this allows better overlapping with other object, for example. Safari, in particular, seems prone to clipping the edges of the effect, so it’s a bit fragile compared with integrating it in the image. Here, then, are plain images without the glow — to which the glow can then be applied in CSS. Without the glow, the “Cambridge” connection disappears; the glow is considered part of the logo, so these aren’t intended to be used “naked". The glow can be relatively slightly larger with smaller images to increase visibility (not used for the image-only version where there is less risk of overlap with other objects hiding the glow). Again, please pick a suitable resolution to manage file size.

These use a Cambridge Blue drop shadow (tripled for density):
filter:drop-shadow(0px 0px npx rgb(163,193,173)) × 3, where n is shown below.

Alternatives are available in smallish resolutions, sized to allow the glow to be added (not tightly cropped):

Lighter version for light backgrounds

Monochrome version

Glow as post-process, monochrome

Note: These versions have not been tightly cropped, so the images contain space for the glow.

Colour-reduced versions

While the pot of winks works best as a “realistic” image, not all printing processes support a full range of colours. In some cases one of the alternative logos would be a better option, but for consistency of branding, simplified forms are available. Note that, without the colours drawing the connection to winks, the polite objects that the monochrome ones resemble are some designs of bottle stopper or honey dipper, and they resemble... some other objects commonly described as “ribbed"... as well, so please think carefully before using them and ensure that the context is obvious.

These are all resolution-independent line art; see the PNG generator if you need a specific resolution.