So, I suspect it's legit. It's a case of an author leaning on a crutch for writing, but we're here to judge the results, not the phasing.

1 header image

1 image showing in process

1 image explaining lightfastness

3 images explaining the importance of lightfastness

1 image explaining the measurement process

1 image linking to another article diving much deeper into the methodology

1 image linking to another article on a different color pencil concern (layering)

1 image representing each brand-line's lightfastness

Every single one of those images seemed relevant to the concept presented and clarified something that would have been difficult to articulate succinctly in writing. For example, the "how was this measured" is a lot easier to understand once you've seen the grid of squares before and after than it would be to try and articulate the fading of colors in small squares in text.

There's LOTS of individual images on specific brands, but given their wild degree of variance, I think it's really useful to perceptually see what's going on with each one.

I'm curious, where do you feel the images were "spammy"? It's a conclusion I heartily disagree with, but would love to understand.

There's more high quality engineering discipline in this 'non-engineering' article than in seemingly a lot of self-professed software engineering today ;)

Going through old photo albums that my parents have show a lot of fading as well, even though the pictures themselves were kept in photo albums in the dark for many years. We have negatives for some of those photos, which when scanned are bright and vibrant, but the prints vary significantly.

I did this for a single color from a single printer—the black toner from my Brother laser printer. I left it in my West facing office window for about 18 months. On the BACK SIDE I labeled it with pen. The pen on the back faded to almost nothing but the toner did not fade at all.

I did not do monthly scans, that would have been a better "experiment", but I was satisfied that a B&W laser print would last a very long time.

Maybe I should lightfast test my Brother Laser and my HP Inkjet (with Black Pigment based ink).

I thought that pigment based inks would be both waterproof and lightfast. Since I started to airbrush watercolor over my HP prints I am now very aware that these pigment based inks are not waterproof, even after long drying times.

Look at all the red-white-and-blue bumper stickers. They are usually white-and-blue.

Around here, we have school buses with a sticker on the back, announcing that they don't turn right on RED (with "RED" being in heavy letters, and colored red).

They frequently say that they don't turn right on.