 |
|
|
|
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Oleguer Vilella wrote:
> Well, I've had a lot of problems with a printing shop, because they had a
> plotter, but the girl that knew how to use it wasn't there (she was outside
> for holidays).
> So Slime's problem is very usual, at least for me. The formats is another
> problem too. I don't why, but some shops want a .tiff, others a .PSD...
Oh yes, and some others only take _vector_ graphic formats for things like
t-shirts (a "professional" one, not those copy shops that do t-shirts as
well). Just last week I had a friend call me and ask what that was supposed
to mean. She was apparently "helped" by a clueless employee. She only had
a PDF document I had created for her long before with Illustrator - as
Illustrator is able to keep all additional information even in a PDF that it
needs, while at the same time only requiring Acrobat Reader to display and
make simple printouts, that is a good format for handing to friends and
still being usable by any qualified user of Illustrator.
Of course she was told that PDFs could _not_ be used. Only after supplying
her with instructions that Illustrator could very well open it and get a
valid "vector graphic" from it, it worked out. She still told me that the
clueless employee was all the time wondering why someone would use PDF for
interchange. Obviously they don't careto think where their customers would
get the software they use from. After all, not everybody qualifies for a
student or other discounted license for Illustrator ;-)
Of course, there is nothing keeping anybody from embedding an appropriately
sized bitmap image in a vector graphic format. Nor would that print shop
have any problem with a plain bitmap image of reasonable resolution and
size. But a clueless employee would. I suppose there just isn't enough
money in this to make it worthwhile to hire qualified staff any more :-(
Thorsten
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On 26 Aug 2005 05:14:51 -0400, Warp <war### [at] tag povrayorg> wrote:
>Stephen McAvoy <mcavoys[at]aol[dot]com> wrote:
>> Screen size, 1000 pixels width fills a 10 inch wide screen gives to
>> some minds, 100 ppi.
>
> But I don't understand how an image file can have a PPI.
> The computer probably doesn't even know the physical size of your
>monitor. How can it figure out its PPI? And even if it figured it out,
>what would it change in the image file? Would the image file somehow
>change with a different PPI?
Of course you are right I know pixels are dimensionless but the
average user thinks a pixel does have two dimensions. I am talking
about people needing something tangible to hang an idea on, to get a
working concept.
Printers are used to working in picas or points and they have
dimensions so it follows (erroneously) graphic images in ppi have a
dimension.
I think PPI is a left over from DTP.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Warp wrote:
> But I don't understand how an image file can have a PPI.
> The computer probably doesn't even know the physical size of your
> monitor. How can it figure out its PPI?
In fact, it likely does! DDC carries information about the physical
dimensions in centimeters. And the DDC extensions for digital displays
provide the pixel width and height (separately, of course) of to 0.01
millimeter precision. You can even get information about the RGB pattern
used by the display. All displays with DVI interface are required to
support DDC, and even most VGA monitors have supported DDC for many years.
DDC is the feature that allows i.e. Windos or Mac OS to detect the valid
display settings you may select. It also allows you to modify some
parameters of _some_ displays, i.e. brightness or contrast via your computer
rather than pressing buttons (an optional feature, depends on display!).
To get an overview of all the information flowing between your monitor and
your computer, check out <http://www.vesa.org/Public/EEDIDguideV1.pdf> (for
most displays) and <http://www.vesa.org/Public/EDID%20EXTENSIONS/DIEXT.pdf>
(for additional information supplied by digital displays).
Thorsten
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Thorsten Froehlich wrote:
>
> Sorry to say, but your guessing is not only wrong but also superfluous:
> Photoshop has two modes of operation for changing the resolution. This
> is easily controlled in the dialog you mentioned with the "Resample
> Image" option. Disable it, and Photoshop just changes the resolution,
> which effectively changes the image size in real-world units (i.e.
> centimeters, inch, etc) without changing any pixel data.
Yes thanks for clarifying that, and that calculation seems to be
straight forward. Using a .bmp image I rendered in POV that is 800
pixels wide, if I enter 300 pixels/inch in the box instead of 72, it
automatically updates the document width box to read 800/300 or 2.667
inches.
> hand, if you enable "Resample Image", Photoshop will interpolate (using
> the specified method in the popup menu next to the resampling checkbox)
> the pixel data maintaining the same image size in real-world units.
Yes, and it produces a new image (which
can be resaved) at the increased resolution needed to support the
increased ppi. So my 800 pixel wide image is resized to 800*300/72 or
3333 pixels wide. Whether or not this new higher resolution image
offers any truely new information can be debated. My
inclination is to say it does not.
But what is mysterious to me is the calculation that happens when
you click "Auto" on that dialog box with resample turned on. That
allows you to set a "lines/inch" value which seems to default to 133
lines/inch. What is opaque to me is two things. What is the
significance of 133? And how is it used to produce the suggested
pixels/inch value? For my original 800 pixel wide image, with resample
on, and using the default lpi value, the "auto" ppi value becomes 266
and the new image resolution becomes 2956 pixels wide. I don't see the
connection between these numbers.
>
> About pixels:
>
> A pixel is nothing more than an atomic unit of color information. It
> has no resolution whatsoever, it does not have a unit it is measured in.
>
> The resolution is implicitly defined by taking a (usually rectangular)
> block of many pixels, commonly called an image, which is a specified
> number of pixels wide and high. You then can define that the width of
> the image, lets say it is 1000 pixels, shall be interpreted as being 2
> real-world units in width.
>
> A real world unit could for example be an inch. In this case, there
> would be 1000 pixels to be fitted such that they are two inches in
> total. Thus, each pixel is interpreted to be 2 inch divided by 1000
> pixel, which equals 500 pixels per inch. You can just as well replace
> the two by 200, and then you get 5 pixels per inch. Or you use some
> other unit to map the pixel to. The essence is, a pixel has no
> dimensions, and thus no unit can measure its size.
>
> In summary: A pixel is just a color information you can interpret to
> have any width and any height you like. And that is what is referred to
> as resolution.
>
Yes I believe I understand these concepts to the extent you have
explained them.
For if you have a printer that is *finally* going to produce the real
world image at the specified real world size, the ppi can tell it the
intended density of the *color information*. Because how the printer
translates this information into real world ink dots is still flexible.
It might use a ratio of 1 pixel = 1 dot, but it doesn't have to. It
could also use many dots to translate one pixel of color information,
lets say 1 pixel = 20 dots.
If this were not true, it seems to me that very high resolution
printers, or even printers produced for the consumer market which boast
dpi resolutions of up to 5600, would only be usefull for producing very
find grained images beyond what is necessary for the unaided eye.
Are these valid calculations?
A 6 magapixel camera could produce a picture in a 4x6 aspect ratio that
has a resolution of 2000x3000=6000000 pixels maximum.
This resolution could produce:
an image of 20 x 30 inches at up to 100 ppi density
an image of 6.6 x 10 inches at up to 300 ppi density
an image of 4 x 6 inches at up to 500 ppi density
an image of .4 x .6 inches at up to 5000 ppi density
But when it comes to making the print, the upper limit also is affected
by the "resolution" that the printer is capable of, expressed in dpi.
So if a printer has a maximum resolution of 5000 dpi, it could produce
the 4 x 6 image and use 10 dots per pixel to improve its own color
handling, or it could produce a .4 x .6 inch image using 1 dot per pixel.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
"Markk" <Markk> wrote:
> I am a very new user to POVRAY.
>
> I have rendered and saved my image as an uncompressed Targa file. The image
> looks great, but it is only 72 ppi. Is there a way to set the ppi during
> rendering in POVRAY? How do people generete publication quality images with
> POVRAY???
>
> Thanks,
>
> MARKk
To change the dpi do this:
- Open Photoshop and create an image with the size you want to print (using
real world units (mm, cm...) and set it to 300 dpi.
- go to image>image size..., use the pixel size in POV-Ray
- render your image and open in photoshop
- go to image>image size...
the size you specified in POV will be the same in the pixel size, but the
image will have 72dpi and will be larger in (mm, cm...)
- Now you just have to change the dpi to 300.
Wagner
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
> To change the dpi do this:
> - Open Photoshop and create an image with the size you want to print (using
> real world units (mm, cm...) and set it to 300 dpi.
> - go to image>image size..., use the pixel size in POV-Ray
> - render your image and open in photoshop
> - go to image>image size...
>
> the size you specified in POV will be the same in the pixel size, but the
> image will have 72dpi and will be larger in (mm, cm...)
>
> - Now you just have to change the dpi to 300.
UNCHECK THE "RESAMPLE IMAGE" OPTION
> Wagner
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
"Markk" <Markk> wrote:
> I am a very new user to POVRAY.
>
> I have rendered and saved my image as an uncompressed Targa file. The image
> looks great, but it is only 72 ppi. Is there a way to set the ppi during
> rendering in POVRAY? How do people generete publication quality images with
> POVRAY???
>
> Thanks,
>
> MARKk
If you want to render a 10x8 inch image at 300 dpi/ppi just multiply
the width and height of the final dimension by the required resolution.
Thus:
10 inches x 300 dpi = 3000 pixels wide
8 inches x 300 dpi = 2400 pixels wide
Now render your image setting W to 3000 and H to 2400 in your ini
file (see the POV documentation on how to do this). In your image
processing program, just scale the image to the required dimension in
inches with the resolution set to 300 ppi.
Perhaps the (edited) ini file below will be of use; I use it for most of my
work.
Best wishes,
Nicholas
; ====================================================================
; Persistence of Vision Raytracer Version 3.5 INI File
; ====================================================================
; File: RES.ini
; Description: INI File
; Date: 15th October 2002
; Author: Nicholas Shea
; Email: nic### [at] tiscalicouk
; --------------------------------------------------------------------
; Height and Width of output in pixels
; --------------------------------------------------------------------
; ==== SYSTEM ==== ASPECT RATIO ==== DESCRIPTION
; ==== PAL ==== 1.25 ==== British TV (Phase Alternating Line)
; ==== 4:3 ==== 1.33333333 ==== Standard Monitor
; ==== NTSC ==== 1.481481 ==== American TV (National Television
Society of America)
; ==== 16:9 ==== 1.777777778 ==== WideScreen
; == STANDARD GRAPHICS CARD DVD
[DVD 1]
+H576
+W1024
[DVD 2]
+H600
+W1027
[DVD 3]
+H900
+W1600
; == 1125/60 HDTV
[HDTV 1]
+H1125
+W2000
[HDTV 2]
+H1200
+W2133
[HDTV 3]
+H1500
+W2666
[HDTV 4]
+H1800
+W3200
[HDTV 5]
+H2100
+W3733
[HDTV 6]
+H2400
+W4266
[HDTV 7]
+H2700
+W4800
[HDTV 8]
+H3000
+W5333
[HDTV 9]
+H3300
+W5866
[HDTV 10]
+H3600
+W6400
[HDTV 11]
+H3900
+W6933
[HDTV 12]
+H4200
+W7466
[HDTV 13]
+H4500
+W8000
[HDTV 14]
+H4800
+W8533
[HDTV 15]
+H5100
+W9066
[HDTV 16]
+H5400
+W9600
[HDTV 17]
+H5700
+W10133
[HDTV 18]
+H6000
+W10666
[HDTV 19]
+H6300
+W11200
[HDTV 20]
+H6600
+W11733
[HDTV 21]
+H6900
+W12266
[HDTV 22]
+H7200
+W12800
; Standard 1.33 ratio
[1.33 1]
+H240
+W320
[1.33 2]
+H480
+W640
[1.33 3]
+H600
+W800
; Widescreen 2.67 ratio 8" wide at 300 dpi
[Widescreen 8]
+H899
+W2400
; Widescreen 2.67 ratio 1" wide at 300 dpi
[Widescreen 1]
+H112
+W300
; Widescreen 2.67 ratio 1.5" wide at 300 dpi
[Widescreen 1.5]
+H168
+W450
; Widescreen 2.67 ratio 2" wide at 300 dpi
[Widescreen 2]
+H225
+W600
; Widescreen 2.67 ratio 2.5" wide at 300 dpi
[Widescreen 2.5]
+H281
+W750
; Widescreen 2.67 ratio 3" wide at 300 dpi
[Widescreen 3]
+H337
+W900
; Widescreen 2.67 ratio 4" wide at 300 dpi
[Widescreen 4]
+H450
+W1200
; Widescreen 2.67 ratio 6" wide at 300 dpi
[Widescreen 6]
+H674
+W1800
; Widescreen 2.67 ratio 8" wide at 300 dpi
[Widescreen 8]
+H899
+W2400
;====
; 36" Square at 300 dpi
[Square 36]
+H10800
+W10800
; 30" Square at 300 dpi
[Square 30]
+H9000
+W9000
; 24" Square at 300 dpi
[Square 24]
+H7200
+W7200
; 20" Square at 300 dpi
[Square 20]
+H6000
+W6000
; 15" Square at 300 dpi
[Square 15]
+H4500
+W4500
; 12" Square at 300 dpi
[Square 12]
+H3600
+W3600
; 10" Square at 300 dpi
[Square 10]
+H3000
+W3000
; 8" Square at 300 dpi
[Square 8]
+H2400
+W2400
; 6" Square at 300 dpi
[Square 6]
+H1800
+W1800
; 4" Square at 300 dpi
[Square 4]
+H1200
+W1200
; 2" Square at 300 dpi
[Square 2]
+H600
+W600
; 1.5" Square at 300 dpi
[Square 1.5]
+H450
+W450
; 1" Square at 300 dpi
[Square 1]
+H300
+W300
; 0.75" Square at 300 dpi
[Square 0.75]
+H225
+W225
; 0.5" Square at 300 dpi
[Square 0.5]
+H150
+W150
; 0.25" Square at 300 dpi
[Square 0.25]
+H75
+W75
; Monitor screen
[My Monitor]
+H768
+W1024
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Nicholas Shea wrote:
> "Markk" <Markk> wrote:
>
>>I am a very new user to POVRAY.
>>
>>I have rendered and saved my image as an uncompressed Targa file. The image
>>looks great, but it is only 72 ppi. Is there a way to set the ppi during
>>rendering in POVRAY? How do people generete publication quality images with
>>POVRAY???
>>
>>Thanks,
>>
>>MARKk
>
>
> If you want to render a 10x8 inch image at 300 dpi/ppi just multiply
> the width and height of the final dimension by the required resolution.
> Thus:
>
> 10 inches x 300 dpi = 3000 pixels wide
> 8 inches x 300 dpi = 2400 pixels wide
>
> Now render your image setting W to 3000 and H to 2400 in your ini
> file (see the POV documentation on how to do this). In your image
> processing program, just scale the image to the required dimension in
> inches with the resolution set to 300 ppi.
>
> Perhaps the (edited) ini file below will be of use; I use it for most of my
> work.
>
> Best wishes,
>
> Nicholas
>
Nicholas,
I've been following this thread because I've had much the same question. Just
no need to have it resolved so I never asked it. Your answer cleared things up
for me immensely.
Thanks,
Tony
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Nicholas Shea wrote:
>
>
> If you want to render a 10x8 inch image at 300 dpi/ppi just multiply
> the width and height of the final dimension by the required resolution.
True as long as dpi = ppi.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Jim Charter <jrc### [at] msncom> wrote:
> Nicholas Shea wrote:
>
> >
> >
> > If you want to render a 10x8 inch image at 300 dpi/ppi just multiply
> > the width and height of the final dimension by the required resolution.
>
> True as long as dpi = ppi.
Technically you are right, though in this case they are synonymous (and the
information given will produce the correct result). Those wanting a good
reference on this subject might consider:
Scanning & Printing by Anton & Peter Kammermeier
(Published by Butterworth Heinemann, ISBN 0 7506 0539 1)
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
|
|
