[Leica] Tina and Digital (was, Enlarger

[mcyclwritr at comcast.net (mcyclwritr@comcast.net)]

Yep, that'd ought solve the whole, dang digital dilemma for Marc. 
If he doesn't stab his eyes out, first. 

Chris Lawson

 -------------- Original message ----------------------
From: Barney Quinn <bquinn@sgi.com>
> 
> 
> Marc,
> 
> I'll give this a try. There are, in general, two ways to store an image on 
> a
> computer. One is called vector format. In vector format you don't store the
> image, you store the instructions for making the image. In the old days a
> vector, in basic physics, was a line which had both magnitude and 
> direction.
> In vector graphics you store an image as a set of instructions which say
> things like draw an orange line from this point to that point. This is how
> postscript works. It is a set of instructions which describe how to make 
> the
> image in question. Postscript files are plain text files and if you want 
> you
> can open one up with a text editor and actually look at the instructions. 
> If
> you are really adventurous, and if you know postscript very well, you can
> even take a text editor or a word processor and write out all the
> instructions to make an image out by hand. But, all you need to remember is
> that in vector graphics you don't store the image, you store the 
> instructions
> for making the image. It's the recipe, but not yet the dinner you are going
> to serve.
> 
> The other way to store or represent an image as as what is called a bit 
> map.
> This works the same way as a picture in a newspaper does. The image is 
> broken
> down in to a bunch of dots. Each dot is stored as a number, or a series of
> numbers, which represent the things you need to know about the dot such as
> its color. These dots are usually called pixels. You could store a very 
> crude
> image by breaking it down into a series of dots which were either black or
> white. If you represented each black dot with a zero and each white dot as 
> a
> 1 then you could store the entire image by storing the 1's and 0's which
> represented the image as a file on your computer. This is exactly how 
> digital
> photography works, only more information is stored because you need more
> information other black or whit to make a continuos tone image. If you 
> wanted
> to compare an image made with just ones and zeros to conventional 
> photography
> it would look like something printed on litho paper because there would be 
> no
> grays. In a slightly more sophisticated system rather than describing each
> dot or pixel with a 0 for black or a 1 for which we could describe it with 
> a
> number from 0 to 7 where the numeric value told us how gray the dot was,
> sorta like the zone system.
> 
> There is a tug of war going on between these two approaches. Vector format 
> is
> useful for some things, such as line drawings, of a page of text, because 
> it
> takes less space to store the instructions to make the image that in would 
> to
> store the actual image. But, as an image becomes more and more complex you
> need more and more instructions in order to store it in vector format. In 
> the
> case of something like a photograph the amount of space you would need to
> store the instructions to make the image can get to be more than the amount
> of space needed to store the image as a bit map. What this means is that it
> takes less space to actually store the image than it does to store the
> instructions for making the image. There is a slight complication here, 
> which
> we will not go into at this point. Imagine a black and white image with a
> high white cloud in it. That is a lot of white, and it takes a lot of 
> numbers
> to describe it.
> 
> There are techniques, called data compression, which will let you store the
> image of the cloud without actually having to store all the ones and zeros
> which make up the cloud. This is called data compression. But, here's an 
> idea
> of how it works. Let's say you wanted to draw a line which ran vertically 
> up
> and down the page which was ten inches long, and let's say that you made 
> your
> image by storing 300 pixels, or dots, for every inch the line was long. In
> the real world computers store information using groups of eight 1's and 
> 0's
> called bytes. In the most basic real world graphic systems one dot, or 
> pixel,
> is stored as a byte or group of eight ones or zeros. To represent the ten
> inch line would take 10 times 300 pixels, or 3,000 bytes of space. It 
> takes a
> lot less space to say start here, and go north for 3,000 dots. The first is
> bit format, the second is vector format, and the difference can be thought 
> of
> as data compression.
> 
> Here's where the rubber hits the road. A bit mapped image is just a bunch 
> of
> ones and zeros stored inside your computer. A vector image is nothing more
> that a set of instructions showing how to draw the image. Neither is an
> image. Both are just a lot of data which is unintelligible to a human. To
> actually get a picture on the wall it has to be printed. This is done with
> something called a rendering engine. Computer geeks use the term engine 
> for a
> program which does the same task over, and over.
> 
> The easiest way I know to answer your question about the meaning of the 
> term
> RIP is to consider what happens when a line drawing is printed out on a 
> piece
> of paper. Let's say that you are using a printer which prints its images at
> 300 dots to the inch. What that means is that a black square one inch by 
> one
> inch would be made up of three hundred dots across, running from left to
> right, and this would happen 300 times running down the page. When the
> printer printed the image it would start and put 300 black dots on the page
> running from right to left.  Then it would finish running across the page.
> The print head which made the dots would move back to the left hand side of
> the page, and page would be advanced 1/300 of an inch, and the print head
> would make 300 more black dots. This process would repeat it self until 
> both
> the one inch by one inch square and the page had been completed. This 
> should
> also give us a hint about why this is am important question. A black square
> an inch by an inch at 300 dots to the inch is made up of 300 x 300 or 
> 90,000
> dots. The amount of information you have to store and manage goes up by
> squares as the size of the image increases.
> 
> A TV set makes an image by sweeping a beam of electrons across the screen,
> causing the appropriate "dots" to "light" up as it goes. When it is done 
> with
> the first line it skips down a line and does another. It works its way down
> the page first doing all the odd numbered lines and then comes back up to 
> the
> top and does all the even numbered lines. This is called interlacing, and 
> we
> aren't going to go into why it's done that way today. This pattern or 
> across,
> down, across, down, across is called a raster. I have no idea why. A 
> printer
> works the same way, only it doesn't skip lines. It does the first, then the
> second, then the third line. Because of the similarity of how a printer 
> and a
> TV work people started calling an image inside a printer a raster, too. RIP
> has three meanings which I know of. The first is Rest in Peace. Most people
> by now are probably wishing I had done that five paragraphs ago. The second
> is Raster Image Processor, and the third is Raster Image Profile.
> 
> All printers have A RIP, or raster image processor built into them. Let's 
> say
> that you want to print an image which is stored in vector format. First you
> have to convert the instructions for making the image into ones and zeros 
> or
> pixels. This is done by a piece of software called a rendering engine. In 
> the
> case of postscript the instructions which make up the image are rendered by
> something called a postscript interpreter. In the case of a compressed bit
> map image the image has to be uncompressed before it can be printed. The
> resulting ones and zeros are now handed to something called a RIP, or 
> raster
> image processor. The RIP converts the ones and zeros into the back and 
> forth
> and up and down instructions that the printer needs to actually put the 
> image
> on paper. Every engineer on the list is probably cringing at this crude
> generalization, but it is the basic idea.
> 
> Now, to the other meaning of RIP. Raster Image Profile. The world is not an
> ideal place, Physical systems are not ideal. Corrections need to be made to
> the information stored in the computer which represents the image in order 
> to
> get it to look "right" when it is printer out. You might, for instance, 
> have
> to make the red's a little bluer in order to get them to look right. The 
> best
> way I can explain a Raster Image Profile is that it is the set of 
> corrections
> which must be made to get the image to look "right" in the real world 
> using a
> specific printer and piece of paper. If is very much like the orange mask 
> in
> a color negative, or the correction pack which you use during color 
> printing
> to compensate for things to get the image to look proper.
> 
> May God forgive me for this unending string of over simplifications. I hope
> it helps.
> 
> Barney
> 
> 
> 
> Marc James Small wrote:
> 
> > At 05:25 PM 2/6/06 -0800, Frank Filippone wrote:
> > >Think.... RIP= Ripped O..
> > >
> > >That is pretty close, and 60's Lingo, so that should work for you....
> >
> > I am even more lost.  "Ripped Off Plums"?  I am really at sea here and 
> > the
> > boat is sinking rapidly.  I do not need hints.  I need reality.
> >
> > You folks are not being much help at all.
> >
> > Marc
> >
> > msmall@aya.yale.edu
> > Cha robh bàs fir gun ghràs fir!
> >
> > NEW FAX NUMBER:  +540-343-8505
> >
> > _______________________________________________
> > Leica Users Group.
> > See http://leica-users.org/mailman/listinfo/lug for more information
> 
> --
> Barney Quinn, Jr.
> (301) 688-1982 (O)
> (240) 535-3036 (C)
> (877) 220-0981 (P)
> 
> 
> 
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