images to print - some confusions

[Ben]

Hi all,

I normally scan photos and create various digital arts/designs "just
for the web". So I am not too familiar with printing my works as to
how it appears on paper. Now I need to print some of my works. I have
to send my works to some printing press. I need to print with the
width of 10in at 200 dpi.

What I've realised now is- for printing a 10in x 10in image at 200dpi,
I need at least 2000 x 2000 pixels image. I normally create my images
at the size of 800 x 800 pixels. Now it seems like if I am to print
10in x 10in image (maintaining good quality), either I'll have to
recreate my work (which seems tedious and virtually impossible) or I
shouldn't even bother printing at 10in x 10in. Am I right? Is there a
better solution for this?

I'm also intrigued by the space it takes to save a 2000 x 2000 pixel
image. One psd image can take 10MB or more if I am to save as 2000 x
2000 pixels. I can't save my images as jpeg. I need to save them as
psd format cause I need to preserve layers. Is there a way to optimise
this or is this just a reality of print work that I'm not familiar
with?

The more I think about it, the more I get confused. One more question
about scanning. When I scan my photo (6in x 4in) to get output of
2000x2000 pixels, isn't there a lot of interpolation done as compared
to 800x600 pixels? Then what about the quality of 2000x2000 pixel
image- isn't it degraded? Then I guess it's better to scan larger
image to get a bigger resolution. Am I right?

Hope some of you can clarify...
Thanx
Ben

 

[Scott W]

It is going to be pretty hard to get a good looking 10 by 10 print from
a 800 x 800 pixel image.

2000 x 2000 is small by todays standards. I routinely work with 5400 x
3600 images, they take up a lot of room on the disk, depending on how
many layers 200 MB or so, but that is why I bought a large hard drive.
If 10MB seems like a large file to you then you really need to go out
and buy a new hard drive, I am using a 250 gig external drive and that
seems to be working well.

Scott

 

[Bas v.d. Wiel]

Hi all,

I normally scan photos and create various digital arts/designs "just
for the web". So I am not too familiar with printing my works as to
how it appears on paper. Now I need to print some of my works. I have
to send my works to some printing press. I need to print with the
width of 10in at 200 dpi.

What I've realised now is- for printing a 10in x 10in image at 200dpi,
I need at least 2000 x 2000 pixels image. I normally create my images
at the size of 800 x 800 pixels. Now it seems like if I am to print
10in x 10in image (maintaining good quality), either I'll have to
recreate my work (which seems tedious and virtually impossible) or I
shouldn't even bother printing at 10in x 10in. Am I right? Is there a
better solution for this?

I'm also intrigued by the space it takes to save a 2000 x 2000 pixel
image. One psd image can take 10MB or more if I am to save as 2000 x
2000 pixels. I can't save my images as jpeg. I need to save them as
psd format cause I need to preserve layers. Is there a way to optimise
this or is this just a reality of print work that I'm not familiar
with?

The more I think about it, the more I get confused. One more question
about scanning. When I scan my photo (6in x 4in) to get output of
2000x2000 pixels, isn't there a lot of interpolation done as compared
to 800x600 pixels? Then what about the quality of 2000x2000 pixel
image- isn't it degraded? Then I guess it's better to scan larger
image to get a bigger resolution. Am I right?

Hope some of you can clarify...
Thanx
Ben

You might get away with a 800x800 pixel original if the colours are very
light and it doesn't contain much really sharp contrast along diagonal
lines (where you would see the stair-stepping pixelation effect called
aliasing).
When printing to an actual four colour offset printing press (for
publication?) you can usually get away with slightly lower resolutions but
not much and I'd say 800x800 is usually really too small to be useful for
this kind of job. I'd consider 2000 pixels wide an absolute minimum to be
useful for printing on a press.
The question about scanning isn't straightforward to answer. Much depends
on the hardware you use and on the quality of your original. Scanning from
prints is always a lot less desirable than using film since prints have
much lower colour depth and resolution. Assuming you shoot on 35mm film
(digital wouldn't need scanning), you can get very good results suitable
for professional printing from many photo labs these days. Even the one
hour shops have started putting film onto CD-R recently. They charge
slightly more than they do for small prints, but I end up with nice
3000x2000 pixel (approximately) images. You should ask around in your
area. You certainly won't exhaust the resolution of a 35mm negative when
you scan it at 2000x2000 pixels as long as the scanner can truly handle
it. Check the optical resolution for that. Interpolation is utterly
useless marketing-speak (there _ARE_ no true 19200dpi. scanners that you
can buy at Dixons) and Photoshop generally seems to do a better job of it
anyway. Many cheap minilab film prints I see actually are actually
scanned and then printed at 300dpi. It's useless to scan those at any
higher resolution as there is simply no more data in the original.

Bas

 

[Tacit]

What I've realised now is- for printing a 10in x 10in image at 200dpi,
I need at least 2000 x 2000 pixels image. I normally create my images
at the size of 800 x 800 pixels. Now it seems like if I am to print
10in x 10in image (maintaining good quality), either I'll have to
recreate my work (which seems tedious and virtually impossible) or I
shouldn't even bother printing at 10in x 10in. Am I right? Is there a
better solution for this?

Yes, you are right. You must create the work at the intended size and
resulution. It is not possible to take a smaller image and resample it
to create the extra pixels without losing quality; you must start at the
right resolution.

I'm also intrigued by the space it takes to save a 2000 x 2000 pixel
image. One psd image can take 10MB or more if I am to save as 2000 x
2000 pixels. I can't save my images as jpeg. I need to save them as
psd format cause I need to preserve layers. Is there a way to optimise
this or is this just a reality of print work that I'm not familiar
with?

It's reality. Uncompressed, a 2000 by 2000 image is 11.4 MB in RGB, 15.3
MB in CMYK. In the world of print, this is considered tiny. It is more
common to see images for print in the 40-50 MB range for, say, magazine
publishing; a full-spread image is often over 100 MB, and a poster-sized
print can easily be 300 MB or more. That's assuming only one layer. I
routinely work with images well over 400 MB in size, and occasionally
over a gigabyte in size.

The more I think about it, the more I get confused. One more question
about scanning. When I scan my photo (6in x 4in) to get output of
2000x2000 pixels, isn't there a lot of interpolation done as compared
to 800x600 pixels? Then what about the quality of 2000x2000 pixel
image- isn't it degraded?

What is the resolution of your scanner?

If you scan a 5 inch by 5 inch image at 600 pixels per inch, it is the
same number of pixels as a 10 inch by 10 inch image at 300 pixels per
inch.

You rarely use an image over 300 pixels per inch in print. The reason
scanners are capable of resolutions greater than 300 pixels per inch is
in case you need to enlarge the image. If you double the print size of
the image, the resolution goes down by half.

Another thing you may not have considered, though, is this: for print,
you work in CMYK, not RGB. An RGB image can not be printed on a printing
press.

 

[Don Stauffer]

Unfortunately, in answering your first question- yes, if you want decent
ten inch prints, it will require rescanning the images. Interpolation
from 800 pixels to 2000 pixels is asking far too much from software.

Second questions, many scanners do scan with high enough resolution that
they can create 2000 x 2000 images without software interpolation. Some
scan 1200 samples per inch, others 2400 samples per inch.

 

[Dr. Joel M. Hoffman]

What I've realised now is- for printing a 10in x 10in image at 200dpi,

I need at least 2000 x 2000 pixels image. I normally create my images
at the size of 800 x 800 pixels. Now it seems like if I am to print
10in x 10in image (maintaining good quality), either I'll have to
recreate my work (which seems tedious and virtually impossible) or I
shouldn't even bother printing at 10in x 10in. Am I right? Is there a
better solution for this?

You are right. To get a good print, you need 200dpi (even though a
computer monitor is often only 72dpi). An 800x800 image at 10"x10"
is, as you've noticed, only 80dpi. It will look terrible.

There are computer algorithms to add more pixels, but you won't get
any additional information, so what you'll end up with is a computer
version of impressionist art. Sometimes it doesn't look terrible, but
it won't look much like a photograph, either.

-Joel

 

[CSM1]

Hi all,

I normally scan photos and create various digital arts/designs "just
for the web". So I am not too familiar with printing my works as to
how it appears on paper. Now I need to print some of my works. I have
to send my works to some printing press. I need to print with the
width of 10in at 200 dpi.

What I've realised now is- for printing a 10in x 10in image at 200dpi,
I need at least 2000 x 2000 pixels image. I normally create my images
at the size of 800 x 800 pixels. Now it seems like if I am to print
10in x 10in image (maintaining good quality), either I'll have to
recreate my work (which seems tedious and virtually impossible) or I
shouldn't even bother printing at 10in x 10in. Am I right? Is there a
better solution for this?

I'm also intrigued by the space it takes to save a 2000 x 2000 pixel
image. One psd image can take 10MB or more if I am to save as 2000 x
2000 pixels. I can't save my images as jpeg. I need to save them as
psd format cause I need to preserve layers. Is there a way to optimize
this or is this just a reality of print work that I'm not familiar
with?

No way around the size of the file other that compression.

The more I think about it, the more I get confused. One more question
about scanning. When I scan my photo (in x in) to get output of
2000x2000 pixels, isn't there a lot of interpolation done as compared
to 800x600 pixels? Then what about the quality of 2000x2000 pixel
image- isn't it degraded? Then I guess it's better to scan larger
image to get a bigger resolution. Am I right?

Hope some of you can clarify...
Than
Ben

If you scan a 6 x 4 inch photo at 334 dpi, you get a 2004 x 1336 pixel
image. There is no interpolation because the scanner is scanning at or below
the optical resolution that it is capable of (assuming) a 600 dpi or more
scanner.

You did not say what the process of creating your original art work is,
other that you scan photos and combine them in some process to make the
finished product for the web.

I understand that the final image is a 800 X 800 pixel electronic image for
the Web.

For the following process to work you will have to flatten the original
image in Photoshop. (Make a copy first!). You also need a flatbed scanner
that is at least 1200 DPI optical resolution.

This method is not as good as creating an original image at 2000 pixels by
2000 pixels, but it may save you having to recreate images that you already
have.

1. Print the 800 X 800 pixel image at 300 DPI on the best Photo paper using
the Best quality setting of your Photo printer (Six color printer
preferred).

That will get you a 2.67 inch by 2.67 inch print. This print should look
perfect with no flaws.
Try until you get a perfect print.

2. Scan the 2.67 inch By 2.67 inch print at 750 DPI. That will give you a
2000 X 2000 pixel image. Adjust your scanner for the best image from the
print. You may have to touch up the scanned image in Photoshop.

By scanning at 750 dpi you are enlarging the image. You are not creating new
pixels, you are simply enlarging what is there.

3. Print the 2000 X 2000 Pixel scanned and corrected image at 200 DPI on the
best photo paper and best quality print setting, and you will have a 10 inch
by 10 inch print. (And it should look very good!)

4. If you want a 300 DPI 10 inch print, in step 2, scan the 2.67 inch print
at 1125 DPI and print the 3000 x 3000 pixel image at 300 DPI.

This makes a second and third generation image, which is not as good as the
original, but it may be good enough. No software can take a 800 pixel image
and create a 2000 pixel image of any quality.

However, you can enlarge a good print by scanning at a high DPI.

Good luck!

If you want to learn more, go to:
http://www.scantips.com

 

[crescent_au]

CSM1 wrote:

1. Print the 800 X 800 pixel image at 300 DPI on the best Photo paper using
the Best quality setting of your Photo printer (Six color printer
preferred).

That will get you a 2.67 inch by 2.67 inch print. This print should look
perfect with no flaws.
Try until you get a perfect print.

2. Scan the 2.67 inch By 2.67 inch print at 750 DPI. That will give you a
2000 X 2000 pixel image. Adjust your scanner for the best image from the
print. You may have to touch up the scanned image in Photoshop.

so that means scanning at any dpi does not involve interpolation? i'm a
bit confused here again...

Btw, thanx for all the replies. They've been very helpful!

Ben

 

[CSM1]

CSM1 wrote:


so that means scanning at any dpi does not involve interpolation? i'm a
bit confused here again...

Btw, thanx for all the replies. They've been very helpful!

Ben

Interpolation for images begins when you set the image size larger that the
original dimensions. (In an editor).

Interpolation for scanners begins when you scan at a greater than optical
resolution of the scanner. There is no interpolation if you scan at dpi's
less than or equal to the optical resolution of the scanner. (It is a direct
read of the sensor). In the case of less than optical resolution, the sensor
data is actually reduced.

If the scanner had a 1200 DPI optical resolution, and you scanned at 2400
DPI, the software would interpolate the scan from 1200 dpi to 2400 dpi (it
would make up pixels, to double the dpi, but you still have 1200 dpi of
data, because that is all the sensor can produce).

How scanners work.
http://computer.howstuffworks.com/scanner.htm

Resolution and Interpolation.
http://computer.howstuffworks.com/scanner3.htm

 

[Bernie]

Hi all,

I normally scan photos and create various digital arts/designs "just
for the web". So I am not too familiar with printing my works as to
how it appears on paper. Now I need to print some of my works. I have
to send my works to some printing press. I need to print with the
width of 10in at 200 dpi.

What I've realised now is- for printing a 10in x 10in image at 200dpi,
I need at least 2000 x 2000 pixels image. I normally create my images
at the size of 800 x 800 pixels. Now it seems like if I am to print
10in x 10in image (maintaining good quality), either I'll have to
recreate my work (which seems tedious and virtually impossible) or I
shouldn't even bother printing at 10in x 10in. Am I right? Is there a
better solution for this?

I'm also intrigued by the space it takes to save a 2000 x 2000 pixel
image. One psd image can take 10MB or more if I am to save as 2000 x
2000 pixels. I can't save my images as jpeg. I need to save them as
psd format cause I need to preserve layers. Is there a way to optimise
this or is this just a reality of print work that I'm not familiar
with?

The more I think about it, the more I get confused. One more question
about scanning. When I scan my photo (6in x 4in) to get output of
2000x2000 pixels, isn't there a lot of interpolation done as compared
to 800x600 pixels? Then what about the quality of 2000x2000 pixel
image- isn't it degraded? Then I guess it's better to scan larger
image to get a bigger resolution. Am I right?

Hope some of you can clarify...
Thanx
Ben

I think you will get a lot of useful knowledge by taking a look at
http://www.scantips.com/

Bernie

 

[Brian]

No way around the size of the file other that compression.




If you scan a 6 x 4 inch photo at 334 dpi, you get a 2004 x 1336 pixel
image. There is no interpolation because the scanner is scanning at or below
the optical resolution that it is capable of (assuming) a 600 dpi or more
scanner.

You did not say what the process of creating your original art work is,
other that you scan photos and combine them in some process to make the
finished product for the web.

I understand that the final image is a 800 X 800 pixel electronic image for
the Web.

For the following process to work you will have to flatten the original
image in Photoshop. (Make a copy first!). You also need a flatbed scanner
that is at least 1200 DPI optical resolution.

This method is not as good as creating an original image at 2000 pixels by
2000 pixels, but it may save you having to recreate images that you already
have.

1. Print the 800 X 800 pixel image at 300 DPI on the best Photo paper using
the Best quality setting of your Photo printer (Six color printer
preferred).

That will get you a 2.67 inch by 2.67 inch print. This print should look
perfect with no flaws.
Try until you get a perfect print.

2. Scan the 2.67 inch By 2.67 inch print at 750 DPI. That will give you a
2000 X 2000 pixel image. Adjust your scanner for the best image from the
print. You may have to touch up the scanned image in Photoshop.

By scanning at 750 dpi you are enlarging the image. You are not creating new
pixels, you are simply enlarging what is there.

3. Print the 2000 X 2000 Pixel scanned and corrected image at 200 DPI on the
best photo paper and best quality print setting, and you will have a 10 inch
by 10 inch print. (And it should look very good!)

4. If you want a 300 DPI 10 inch print, in step 2, scan the 2.67 inch print
at 1125 DPI and print the 3000 x 3000 pixel image at 300 DPI.

This makes a second and third generation image, which is not as good as the
original, but it may be good enough. No software can take a 800 pixel image
and create a 2000 pixel image of any quality.

However, you can enlarge a good print by scanning at a high DPI.

Good luck!

If you want to learn more, go to:
http://www.scantips.com

I hate to say it Ben, but I would not waste your time reading that
article at www.scantips.com The article rambles on for paragraphs
about an argument that does not even exist, and at the end of the day
tells you what could have been stated in about one paragraph plus a table.
The author of that article clearly has no idea what the "perception" of
72/96 dpi is all about.

Brian.

 

[Shez]

In the faraway land of comp.periphs.scanners, Ben

for printing a 10in x 10in image at 200dpi,
I need at least 2000 x 2000 pixels image. I normally create my images
at the size of 800 x 800 pixels. Now it seems like if I am to print
10in x 10in image (maintaining good quality), either I'll have to
recreate my work (which seems tedious and virtually impossible) or I
shouldn't even bother printing at 10in x 10in. Am I right? Is there a
better solution for this?

In future, yes you need to scan and edit at 2000x2000, then scale down
the end result for your web images.

As for the existing work, well first I would try rescaling it in
photoshop to check for sure how bad it is. In photoshop, simply put in a
resize setting of 10"x10" @ 200dpi. This is basically a 2.5x
enlargement. Now print it out and examine the result. (Depending on your
printer you may need to crop it to 8" wide to fit your paper at actual
size.) A proper printing press output will not look quite the same as
your own printer but you'll be able to tell whether the quality is
acceptable or not.

With the bicubic resampling photoshop uses, jaggies should not be a
problem at 250% enlargement: lines and curves should stay pretty smooth.
But there will be a lack of fine detail, as any feature 1 pixel wide
before will now be 2.5 pixels wide; this will also make fine textures
look rather lumpy or blurry. If you applied any sharpening to the
original image, or if it has undergone jpeg compression at some point,
the resultant "ringing" effect will be exaggerated by the enlargement
and look pretty terrible.

At the end of the day the acceptability of the result depends on whether
it contains a lot of fine detail or textures, which will suffer from
enlargement, or whether it is mainly simple shapes and smooth tones etc
which can be enlarged without much problem. I have often enlarged images
to 200% size with no problem, but equally I've had many that looked
terrible on being enlarged. It also depends on what you or your
publisher consider acceptable!

Incidentally the suggestion of printing out at 300dpi and rescanning at
750 is a red herring. Since the colours in the printout will be made up
of dither patterns of CMYK dots, this will lead to much more quality
loss than simply resampling in photoshop. Even if you have a dye-sub
printer which doesn't use dither patterns, printing at one resolution
and scanning at another still just amounts to a form of optical
resampling, and I would be very surprised if this was better than the
bicubic resampling you can do in software.


--
______________________________________________________

The Peter Principle: In an organisation each person
rises to the level of his own incompetency.
______________________________________________________
Take a break at the Last Stop Cafe: http://www.xerez.demon.co.uk/
Reply-to address for email: mailreply AT xerez.demon.co.uk