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Lossy

In the prior thread, Wolfus asked if “lossy” was a Britishism. It ain’t. And because I’m desperate for stuff to post about at the moment, I shall explain what it is.

“Generation loss” is a thing in graphic arts. It means that every time you make a copy of something — every time it goes down a generation — it loses quality. If you have an illustration, and you photograph it, and then you do a color separation, and then you print it in a magazine…every stage of that process involves a degradation of the original.

Then if you make a photocopy of the magazine article and digitize it to put in your slide presentation…don’t laugh. I often deal with images that are many generations removed from the original.

That’s generation loss; the term “lossy” is used specifically for digital file formats.

The Targa tiff file — which you may never have run across — was a common early digital file format that purported to be lossless. In theory, you could make a tif file of a tif file and every one was as good as the original. Downside: they were huge.

Lots of file formats have used all sorts of clever algorithms to try to squeeze file size without losing quality.

The jpg file came to rule them all because it’s very, very good at the trade off…it can look very good, or it can compress very small, or it can be a compromise, depending on what you ask it to do. That’s what it’s asking when a graphics program gives you a jpg quality slider.

The image at right is a jpg compressed at a quality of about 70% (100% means very little loss, very little compression) and it’s about 36K on the disk. The inset is compressed at around 10% (lots of loss, lots of compression) and is about 7K.

Notice the characteristic big square blocks that are the hallmark of jpg compression. I bet you’ve seen that before! Different lossy formats are ugly in different ways and when I get my Photoshop back, I can show you.

That’s not my big white rooster, by the way. That’s my old lavender hen Violence (may she rest in peace). I’ve had three lavender chickens, and they’ve all hated me.

Comments


Comment from ExpressoBold
Time: November 28, 2018, 9:36 pm

I sent some people here this morning to read the Food Price comments on yesterday’s post… did you notice the traffic increase?

 


Comment from Some Vegetable
Time: November 28, 2018, 10:57 pm

So, “Lossy” is a ‘Term of Art’ among digital graphic artists?

A ‘Term of Art’ is a term that has a specialized meaning in a particular field or profession, and may have different meaning in different fields.

For example a ‘Loser’ might have one specific meaning among the gambling profession, while having a completely different meaning in the Match-Making field.

By the way, as long as I’m guilty of shamelessly and blatantly hijacking the subject, in an attempt to be more interesting about it, I’ll just toss in the fact that professional match making is not only still a Thing in Japan, it’s still a Big Thing. Mrs Vegetable and I know at least three Japanese couples who were married through the process, and it seems to have worked out well for them.

https://www.japantimes.co.jp/news/2018/02/16/national/social-issues/parents-unmarried-offspring-drive-surge-matchmaking-parties/#.W_8ZHYpMGhA

Trying to swerve back on subject, the Term of Art for professional match making, in Japan, is “Omiai” ( literally “looking at one another”) and matchmaker is called a “nakōdo”. The Nakōdo is the go-between, who starts out with what’s essentially a catalog with pictures and profiles. Both parties flip through the book until they find mutually acceptable possibilities to date and things proceed from there. Note that there are not “arranged marriages” as such in that the parents who are paying for the service, aren’t making the decision as to which specific person to marry, just applying a bit of pressure to get married dear; there must be somebody acceptable in that catalog your father paid so much money to the Nakōdo for you to look at.

 


Comment from Timbotoo
Time: November 29, 2018, 12:18 am

Back in the day, around 1988 my mother asked for a copy of a photo I had taken . For the life of me I couldn’t find the negative so I took the photo into a copy shop and they produced a series of prints with different levels of color saturation. They were fantastic and moved the image beyond a photo.

 


Comment from Surly Ermine
Time: November 29, 2018, 8:13 am

Lossy is my eyesight in recent years.

My mother often takes photos of photos. Drives me nuts.

 


Comment from AliceH
Time: November 29, 2018, 3:28 pm

Sometimes weird thoughts pop into my head fully formed. While reading this post I suddenly realized that although as a child I was never much into dinosaurs, I’d have found them fascinating if I’d known they might have looked like big chickens.

 


Comment from Wolfus Aurelius
Time: November 29, 2018, 3:40 pm

Stoaty,

Good to know. If I ever write a story with a character whose experience with photography extends back before the iPhone, I could use this.

 


Comment from can’tharkmycry
Time: November 29, 2018, 4:35 pm

Yes, this was fascinating. Thank you!
Wish you still had the like widget for your posts, and not just the comments. . .

 

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