Re: Software for technical illustrations

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Hal Eckhart <hal@c...> wrote:

> On 7/10/04 4:35 PM, Fred Smith wrote:
>
> >The reason that jpeg is used is because the picture are not

limited

> >to 256 color palette images as in GIF. Rendered/shaded surfaces

are

> >displayed (in Gif) with wide bands of "close" colors from those
> >available in the current color palette. Gradient fills are

humorous.

>
> I'm afraid you missed my entire point. The idea is not that jpegs

and other

> photographic formats are bad, but that they are bad for lines and

text. I fail

> to see why lines and text need more than 256 colors or gradient

anything.

You also fail to see when somebody agrees with you. ;-)

There may be other things in documentation within a .doc file that
are not simple lines like pictures of machined parts. These will be
best displayed with jpg.

>
> I am NOT trying to start a flame war. I'm just stating what I

believe to be

> facts and expressing a little frustration about what I've

encountered over the

> years. Like receiving drawings from clients exported from AutoCad

as JPGs that I

> couldn't read.

I would blame Acad for as much as possible. ;-)

>Only because no amount of zooming or squinting made the
> dimensions legible.
>
> >PDF is Adobe's proprietary format.
>
> This is true. But you can read and write them on nearly any OS

without paying a

> nickel to Abode.
>
> >The image files embedded are Tiffs
>
> Huh? I'm no expert, but I can't believe this is true. My 6.3 K png

turned into a

> tif that is 876 K.

This is an operator issue, not a tiff issue. There are more kinds of
tiff files than most any other. Faxes can be considered tiffs as
well as many others.

>Only a few bits bigger than the bmp format. Converted to a
> pdf, the png is still just 6.3 K.

Png is a lossless and open format that was developed to display
things on the internet. The png export from micrografx programs, now
Corel is superb for that purpose. ( Designer, flowchart, etc)

> Since I mentioned bitmaps before, here's one clarification. Once

again, I'm no

> expert, but it's my understanding that postscript can be a

combination of vector

> and bitmap, compressed and uncompressed.

Yes and as I pointed out this is called a metafile.

>This relates to file sizes accordingly.

It can, but is not always the case. As there can be a lot of overhead
if mixed modes are used.

> A png converted to a ps will be about the same size as the png.

Pure coincidence.

>But a png
> converted to a tif converted to a ps will be nearly twice the size

of the tif.

> My teeny 6.3 K png turned into 1.3 Meg by this method. Only about

200 times

> bigger.

PS and pdf both have various image quality settings. If you set them
the wrong way you will get lousy results, just like you described.
They have sampling and compression capabilities, very similar to the
creation of a jpg.

Here is a link that may give you a hint about Tiff in ps and pdf.
read down to who owns tiff?

http://home.earthlink.net/~ritter/tiff/#whatis

Fred Smith - IMService