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I'm being asked to sell the pics I've been taken at our Western Riding
Club shows, apparently they're good enough people are actually *asking*
to pay money for 'em (cool!)

I show the pics on the club website (cawri.com), at 640x480, which
provides a decent 4x6 print, and encourage folks to print those images
for free.

Now, I've been printing my own photos for years. I just take the
biggest copy I have, and print that at whatever resolution I need,
ignoring ppi, which appears to be at 72ppi on my current images
according to ThumbsPlus. I got decent photos at 8x10, even with my older
cameras, back to 1.5MP. I've been getting excellent photos with 5MP
cameras and above, at 8x10.

Now, I'm looking at something that's explaining resolution vs print
size, and saying for my 6MP camera the max I can print is 10x6 @300ppi.
Hmmm.

My concern is, I'm thinking of providing the digital files rather than
printing them (that was a big pain last time I did it). I was thinking
of providing and charging for the files based on the biggest image it
would print...

So for example, at 72ppi, I could provide a 1024x768 image intended to
print an 8x10.

At 300ppi, I'd have to provide a full-sized 10MP image (3888x2592).

I don't quite understand the difference, since it appears I've been
happily printing at the lower ppi for years without loss of quality -
pictures I've printed have won photo contests, even!

Can someone help explain this discrepancy? I could use some advice as
to the best way to provide digital images to my prospective customers,
that gives them the resolution to print to the size they want, and no
bigger.

Or is there a better way I should be doing this?

Appreciate any advice!

jmc

"jmc" <> wrote in message
news:...
> I'm being asked to sell the pics I've been taken at our Western Riding
> Club shows, apparently they're good enough people are actually *asking* to
> pay money for 'em (cool!)
>
> I show the pics on the club website (cawri.com), at 640x480, which
> provides a decent 4x6 print, and encourage folks to print those images for
> free.
>
> Now, I've been printing my own photos for years. I just take the biggest
> copy I have, and print that at whatever resolution I need, ignoring ppi,
> which appears to be at 72ppi on my current images according to ThumbsPlus.
> I got decent photos at 8x10, even with my older cameras, back to 1.5MP.
> I've been getting excellent photos with 5MP cameras and above, at 8x10.
>
> Now, I'm looking at something that's explaining resolution vs print size,
> and saying for my 6MP camera the max I can print is 10x6 @300ppi. Hmmm.
>
> My concern is, I'm thinking of providing the digital files rather than
> printing them (that was a big pain last time I did it). I was thinking of
> providing and charging for the files based on the biggest image it would
> print...
>
> So for example, at 72ppi, I could provide a 1024x768 image intended to
> print an 8x10.
>
> At 300ppi, I'd have to provide a full-sized 10MP image (3888x2592).
>
> I don't quite understand the difference, since it appears I've been
> happily printing at the lower ppi for years without loss of quality -
> pictures I've printed have won photo contests, even!
>
> Can someone help explain this discrepancy? I could use some advice as to
> the best way to provide digital images to my prospective customers, that
> gives them the resolution to print to the size they want, and no bigger.
>
> Or is there a better way I should be doing this?
>
> Appreciate any advice!
>
> jmc

Sorry but I do not see any problem with what you are already doing, if it
works then keep using the same method.

If it ain't broken then there is nothing to fix.

Cheers.

Pete

"jmc" <> wrote in message
news:...
> I'm being asked to sell the pics I've been taken at our Western Riding
> Club shows, apparently they're good enough people are actually *asking* to
> pay money for 'em (cool!)
<snip>
> Can someone help explain this discrepancy? I could use some advice as to
> the best way to provide digital images to my prospective customers, that
> gives them the resolution to print to the size they want, and no bigger.
>
> Or is there a better way I should be doing this?
>
> Appreciate any advice!
>
Have a look here.
http://www.microsoft.com/windowsxp/u...stquality.mspx

http://www.digicamguides.com/print/ppi-print-size.html

jmc wrote:
> Now, I've been printing my own photos for years. I just take the
> biggest copy I have, and print that at whatever resolution I need,
> ignoring ppi, which appears to be at 72ppi on my current images
> according to ThumbsPlus. [...]

> I don't quite understand the difference, since it appears I've
> been happily printing at the lower ppi for years without loss of
> quality - pictures I've printed have won photo contests, even!

No you haven't. You have taken pictures with a certain amount of pixels
and printing them at a certain physical size. That gives an effective
ppi that has absolutely nothing to do with whatever ppi is stated in
the meta-data for the image.

It's a common mistake: The ppi stated in the image is just a suggestion
for the print-resolution (and size, when we combine it with the amount
of pixels). Suggestion being the important word here. You have
overruled it when you have been printing. Continue doing that and all
will continue to be fine.
--
Toke Eskildsen - http://ekot.dk/

jmc wrote:

> I'm being asked to sell the pics I've been taken at our Western Riding
> Club shows, apparently they're good enough people are actually *asking*
> to pay money for 'em (cool!)
>
> I show the pics on the club website (cawri.com), at 640x480, which
> provides a decent 4x6 print, and encourage folks to print those images
> for free.
>
> Now, I've been printing my own photos for years. I just take the
> biggest copy I have, and print that at whatever resolution I need,
> ignoring ppi, which appears to be at 72ppi on my current images
> according to ThumbsPlus. I got decent photos at 8x10, even with my older
> cameras, back to 1.5MP. I've been getting excellent photos with 5MP
> cameras and above, at 8x10.
>
> Now, I'm looking at something that's explaining resolution vs print
> size, and saying for my 6MP camera the max I can print is 10x6 @300ppi.
> Hmmm.


Pixels per inch is the PRINT resolution, not the image resolution.
PPI has nothing to do with the quality of a digtial image file.
The PPI attributed to an image file is meaningless until you actually
print an image.

When you print a digital image, you spread the pixels in the image
across inches of paper. Pixels per inch (PPI) is the number of
pixels you put on each inch of paper. The formula for calculating
PPI is:

Pixels divided by Inches

So.. If you have an image that's 1000 pixels wide and you print it
evenly across 10 inches of paper, you printed it at:

1000 pixels divided by 10 inches of paper = 100 Pixels per inch

If we print this 1000 pixel image across 5 inches of paper, then we
get 1000 pixels / 5 inches = 200 Pixels for each inch of paper,
or in other words 200 PPI.

You MUST consider inches when dealing with Pixels per INCH because
you can't have Pixels per inch without inches Once you grasp the
fact that the PPI of an image is nothing more than the PRINT SIZE then
it all becomes easy

> snip

> So for example, at 72ppi, I could provide a 1024x768 image intended to
> print an 8x10.

No. It's mathematically impossible to spread 1024 pixels across 10 inches
of paper and have 72 pixels on each of paper.

If you spread 1024 pixels across 10 inches of paper, you have

1024 pixels / 10 inches = 102.4 PPI

Despite the fact that ThumbsPlus said the image has 72 PPI, if you
print a 1024 pixel image across 10 inches of paper, you actually
printed it at 102.4 PPI. Whatever software you used to print the
image CHANGED the PPI from 72 to 102.4.

This is why the PPI of an image is meaningless. The practical PPI
doesn't 'happen' until you actually print the image on paper.

> At 300ppi, I'd have to provide a full-sized 10MP image (3888x2592).

Again, to provide a 300 PPI image, you need to know the number of
inches of paper the image will be spread across.

If you want to print a 10x8 image at 300 PPI, then the image file
you use MUST be 3000 X 2400 pixels.

10 inches X 300 PPI = 3000 pixels
8 inches X 300 PPI = 2400 pixels

If you want to print a 6 x 4 image at 300 PPI then the image file
must be 1800 X 1200.

jmc wrote:
> I'm being asked to sell the pics I've been taken at our Western Riding
> Club shows, apparently they're good enough people are actually *asking*
> to pay money for 'em (cool!)
>
> I show the pics on the club website (cawri.com), at 640x480, which
> provides a decent 4x6 print, and encourage folks to print those images
> for free.
>
> Now, I've been printing my own photos for years. I just take the
> biggest copy I have, and print that at whatever resolution I need,
> ignoring ppi, which appears to be at 72ppi on my current images
> according to ThumbsPlus. I got decent photos at 8x10, even with my older
> cameras, back to 1.5MP. I've been getting excellent photos with 5MP
> cameras and above, at 8x10.
>
> Now, I'm looking at something that's explaining resolution vs print
> size, and saying for my 6MP camera the max I can print is 10x6 @300ppi.
> Hmmm.
>
> My concern is, I'm thinking of providing the digital files rather than
> printing them (that was a big pain last time I did it). I was thinking
> of providing and charging for the files based on the biggest image it
> would print...
>
> So for example, at 72ppi, I could provide a 1024x768 image intended to
> print an 8x10.
>
> At 300ppi, I'd have to provide a full-sized 10MP image (3888x2592).
>
> I don't quite understand the difference, since it appears I've been
> happily printing at the lower ppi for years without loss of quality -
> pictures I've printed have won photo contests, even!
>
> Can someone help explain this discrepancy? I could use some advice as
> to the best way to provide digital images to my prospective customers,
> that gives them the resolution to print to the size they want, and no
> bigger.
>
> Or is there a better way I should be doing this?
>
> Appreciate any advice!
>
> jmc

Most folks find a print at less than 150 ppi too soft. When
they buy a print they have already seen, they can't
complain. If you sell the file, you'll get lots of
complaints, not only of the lack of sharpness but also about
other problems, like bad color, when they get prints made at
drug stores and the like.

jmc <> wrote:
>
> I just take the
> biggest copy I have, and print that at whatever resolution I need,
> ignoring ppi, which appears to be at 72ppi on my current images
> according to ThumbsPlus.

As others have said, the real pixels per inch is determined by big you make
the print. In a lot of software, when you see the figure "72 dpi" what it
really means is that the ppi setting in the image file is undefined. The
72dpi figure which a lot of software defaults to may have had some
historical significance (e.g. in the days of black & white newspapers I
think photos used to be printed using a 72dpi dot screen) but is now long
obsolete.

As to what is a reasonable resolution, this depends on the image and how
close you will look at it, but I would consider 100 pixels per inch as the
minimum. When you printed your 640x480 images at 6x4" you were getting
107ppi which looks acceptable but is not especially sharp. 100 ppi is fine
for poster-size prints since they are viewed from some distance, so a
3000x2000 image can be blown up to 30x20" and look very good. In fact most
posters made from 35mm negs are unlikely to have more than 100 ppi of
actual detail in them unless a fine-grained film and tripod was used. And a
quick look at my local free-sheet reveals that modern all-colour newspapers
print images with a dot-screen of about 100 dpi. So we can reasonably call
100ppi "newspaper quality".

Better for general use is 150ppi, and although still lacking very fine
detail this is good enough for many purposes. Magazines typically print
their photos at this resolution. Note though that if you are working
towards publication, an image destined to be printed at 150dpi should start
life as twice that, i.e. 300ppi, otherwise the slight mismatch between
image pixels and printing plate dots will effectively halve the resolution,
giving poor results. This is one of the reasons why you hear people saying
your images should be 300ppi. However for direct photographic or inkjet
printing this should not be a factor and a print from a 150ppi original
will look as good as a colour magazine photo, in fact probably better.

The other reason people talk about 300ppi is that this is about the limit
of human vision when looking at a print from a typical viewing distance
(which varies according to print size). So for razor sharp images, 300ppi
is just about perfect, and anything much more than that is likely to be
wasted, at least in a continuous tone image. Also, traditional photographic
prints have around 300-400ppi in terms of detail, so you might call 300ppi
"photo quality".

As for me, as long as I can print at between 150-300ppi I am happy, though
I prefer 200ppi upwards if possible. At a pinch 100ppi will do, but in that
case I usually resample the image to a higher resolution first to avoid
possible pixellation.

jmc wrote:
> I'm being asked to sell the pics I've been taken at our Western Riding
> Club shows, apparently they're good enough people are actually *asking*
> to pay money for 'em (cool!)
>
> I show the pics on the club website (cawri.com), at 640x480, which
> provides a decent 4x6 print, and encourage folks to print those images
> for free.
>
> Now, I've been printing my own photos for years. I just take the
> biggest copy I have, and print that at whatever resolution I need,
> ignoring ppi, which appears to be at 72ppi on my current images
> according to ThumbsPlus. I got decent photos at 8x10, even with my older
> cameras, back to 1.5MP. I've been getting excellent photos with 5MP
> cameras and above, at 8x10.
>
> Now, I'm looking at something that's explaining resolution vs print
> size, and saying for my 6MP camera the max I can print is 10x6 @300ppi.
> Hmmm.
>
> My concern is, I'm thinking of providing the digital files rather than
> printing them (that was a big pain last time I did it). I was thinking
> of providing and charging for the files based on the biggest image it
> would print...
>
> So for example, at 72ppi, I could provide a 1024x768 image intended to
> print an 8x10.
>
> At 300ppi, I'd have to provide a full-sized 10MP image (3888x2592).
>
> I don't quite understand the difference, since it appears I've been
> happily printing at the lower ppi for years without loss of quality -
> pictures I've printed have won photo contests, even!
>
> Can someone help explain this discrepancy? I could use some advice as
> to the best way to provide digital images to my prospective customers,
> that gives them the resolution to print to the size they want, and no
> bigger.
>
> Or is there a better way I should be doing this?
>
> Appreciate any advice!
>
> jmc

The 72ppi you see usually refers to the most common video display
setting for resolution, and has NOTHING to do with the printing of an
image. If you have a good monitor, you can change that setting to 96,
or even 100 or more, and watch Thumbsplus display that new number.

As for printing, the 'dream number' is 300 pixels/inch, but this is
often more than is necessary for a good image. Something between 150
and 250 pixels/inch is usually more than adequate for 4x6, and some
pictures printed at 8x10 look just fine as low as 150 pixels/inch. I
would shoot for 200 as a good figure, and just forget about that 72
figure since it has nothing to do with printing.