dpi

Wolf wrote:

Help me to understand.

I’ve set my camera takes images at 1600 x 1200 pixels
Size is approx 56cms x 42cms
Resolution is 72 dpi
I’m told that a reasonable print can be made from the above.
However I’m advised that when printing quality images a resolution of approx 300 dpi is necessary
So if I change my resoution to 300 dpi(no resampling) the image size changes to approx 13 x10cms

If I use the resample option then the pixel count chnages to 6666 x 5000 pixels (huge file)
size stays at approx 56cms x 42cms

What am I supossed to aim for ?? Should I change my resolutions? What the best option?

Don’t check ‘resampling’. The PPI value determines how big or how small the pixels are printed, so it is logical that 300 pixels per inch of paper will give you a smaller size print than 72 pixels per inch of paper. A resolution of 72 pixels per inch of paper is indeed too low. You will see the individual pixels and lines in the image become ‘jagged’ if you use 72 ppi. 300 ppi is a good resolution, but don’t see it as the holy grail. If you want to have a print that is a bit bigger than 10 x 13 cm, just do so by using a slightly lower resolution. It will still look fine.

—
Johan W. Elzenga johan<<at>>johanfoto.nl Editor / Photographer http://www.johanfoto.com

On Sun, 30 Sep 2007 06:42:25 GMT, "Wolf" wrote:

Help me to understand.

I’ve set my camera takes images at 1600 x 1200 pixels
Size is approx 56cms x 42cms
Resolution is 72 dpi
I’m told that a reasonable print can be made from the above.
However I’m advised that when printing quality images a resolution of approx 300 dpi is necessary
So if I change my resoution to 300 dpi(no resampling) the image size changes to approx 13 x10cms

If I use the resample option then the pixel count chnages to 6666 x 5000 pixels (huge file)
size stays at approx 56cms x 42cms

What am I supossed to aim for ?? Should I change my resolutions? What the best option?

REsolution on your screen and on the printed page are vastly different things. Do not get confused.

Your image is 1600 x 1200 pixels. That is all you need to know. If you print it at 300 ppi, your image will print at 1600 / 300 inches wide – 5.3 inches (about 13.5 cm).

If you have the resample box checked when you resize your image, Photoshop will add or remove pixels according to a mathematical formula. If you resample up , Photoshop will invent new pixels and add them to your image. The results may or may not be worthwhile, probably not.

(Johan W. Elzenga) wrote:

Wolf wrote:

Help me to understand.

I’ve set my camera takes images at 1600 x 1200 pixels
Size is approx 56cms x 42cms
Resolution is 72 dpi
I’m told that a reasonable print can be made from the above.
However I’m advised that when printing quality images a resolution of approx 300 dpi is necessary
So if I change my resoution to 300 dpi(no resampling) the image size changes to approx 13 x10cms

If I use the resample option then the pixel count chnages to 6666 x 5000 pixels (huge file)
size stays at approx 56cms x 42cms

What am I supossed to aim for ?? Should I change my resolutions? What the best option?

Don’t check ‘resampling’. The PPI value determines how big or how small the pixels are printed, so it is logical that 300 pixels per inch of paper will give you a smaller size print than 72 pixels per inch of paper. A resolution of 72 pixels per inch of paper is indeed too low. You will see the individual pixels and lines in the image become ‘jagged’ if you use 72 ppi. 300 ppi is a good resolution, but don’t see it as the holy grail. If you want to have a print that is a bit bigger than 10 x 13 cm, just do so by using a slightly lower resolution. It will still look fine.

The Whole_Value of the image depends on 3 separated value of W x H x R. Or

"3000-W x 3000-H x 1-PPI" has more value than "1-W x 1-H x 300-PPI"

IOW, when someone says "PPI" doesn’t mean anything and s/he ain’t kidding.

In article <lzHLi.3658$>,
"Wolf" wrote:

However I’m advised that when printing quality images a resolution of approx 300 dpi is necessary
So if I change my resoution to 300 dpi(no resampling) the image size changes to approx 13 x10cms

Yes, that’s correct.

What am I supossed to aim for ??

What do you want to do? How big do you want the printout to be?

—
Photography, kink, polyamory, shareware, and more: all at http://www.xeromag.com/franklin.html

(Johan W. Elzenga) found these unused words:

Wolf wrote:

Help me to understand.

I’ve set my camera takes images at 1600 x 1200 pixels
Size is approx 56cms x 42cms
Resolution is 72 dpi
I’m told that a reasonable print can be made from the above.
However I’m advised that when printing quality images a resolution of approx 300 dpi is necessary
So if I change my resoution to 300 dpi(no resampling) the image size changes to approx 13 x10cms

If I use the resample option then the pixel count chnages to 6666 x 5000 pixels (huge file)
size stays at approx 56cms x 42cms

What am I supossed to aim for ?? Should I change my resolutions? What the best option?

Don’t check ‘resampling’. The PPI value determines how big or how small the pixels are printed, so it is logical that 300 pixels per inch of paper will give you a smaller size print than 72 pixels per inch of paper. A resolution of 72 pixels per inch of paper is indeed too low. You will see the individual pixels and lines in the image become ‘jagged’ if you use 72 ppi. 300 ppi is a good resolution, but don’t see it as the holy grail. If you want to have a print that is a bit bigger than 10 x 13 cm, just do so by using a slightly lower resolution. It will still look fine.

MOST of the ‘in store’ digital printers have a paper resolution of about 200 ppi. Nearly anything with a sharp original will look fine at 150 to 200 dpi.

FWIW: IMHO 1600×1200 is TOO DARN LOW for anything but ‘snapshot size’ prints!

Sir F. A. Rien wrote:

Don’t check ‘resampling’. The PPI value determines how big or how small the pixels are printed, so it is logical that 300 pixels per inch of paper will give you a smaller size print than 72 pixels per inch of paper. A resolution of 72 pixels per inch of paper is indeed too low. You will see the individual pixels and lines in the image become ‘jagged’ if you use 72 ppi. 300 ppi is a good resolution, but don’t see it as the holy grail. If you want to have a print that is a bit bigger than 10 x 13 cm, just do so by using a slightly lower resolution. It will still look fine.

MOST of the ‘in store’ digital printers have a paper resolution of about 200 ppi. Nearly anything with a sharp original will look fine at 150 to 200 dpi.
FWIW: IMHO 1600×1200 is TOO DARN LOW for anything but ‘snapshot size’ prints!

Perhaps you are unfamiliar with the centimeter, but 10 x 13 cm is indeed snapshot size. It’s about 4 x 5 inch.

—
Johan W. Elzenga johan<<at>>johanfoto.nl Editor / Photographer http://www.johanfoto.com

(Johan W. Elzenga) found these unused words:

Sir F. A. Rien wrote:

Don’t check ‘resampling’. The PPI value determines how big or how small the pixels are printed, so it is logical that 300 pixels per inch of paper will give you a smaller size print than 72 pixels per inch of paper. A resolution of 72 pixels per inch of paper is indeed too low. You will see the individual pixels and lines in the image become ‘jagged’ if you use 72 ppi. 300 ppi is a good resolution, but don’t see it as the holy grail. If you want to have a print that is a bit bigger than 10 x 13 cm, just do so by using a slightly lower resolution. It will still look fine.

MOST of the ‘in store’ digital printers have a paper resolution of about 200 ppi. Nearly anything with a sharp original will look fine at 150 to 200 dpi.
FWIW: IMHO 1600×1200 is TOO DARN LOW for anything but ‘snapshot size’ prints!

Perhaps you are unfamiliar with the centimeter, but 10 x 13 cm is indeed snapshot size. It’s about 4 x 5 inch.

Quite familiar with metric, thanks! I was commenting upon the OP’s ‘choice’ of ‘medium’ resolution to TAKE his imagery. Easy to reduce ‘size’, but when you have that ‘great’ shot and can’t get a decent 20 x 26 cm print ???

On 2007-09-30 04:12:25 -0230, "Wolf" said:

Help me to understand.

I’ve set my camera takes images at 1600 x 1200 pixels
Size is approx 56cms x 42cms
Resolution is 72 dpi
I’m told that a reasonable print can be made from the above.
However I’m advised that when printing quality images a resolution of approx 300 dpi is necessary
So if I change my resoution to 300 dpi(no resampling) the image size changes to approx 13 x10cms

If I use the resample option then the pixel count chnages to 6666 x 5000 pixels (huge file)
size stays at approx 56cms x 42cms

What am I supossed to aim for ?? Should I change my resolutions? What the best option?

Never hit the resample option, this will give you the true size when you change the DPI value.
300 dpi is the standar among professional, it is overrated.

Most AM sheetfed and web press will downsample to 235-260 dpi. then you have FM printing on a press that could use more.

your home printer is FM but it’s rip is probably only using 200 dpi or less. Most of us leave at 300dpi so the printer downsamples instead of upsampling at the RIP stage and keep it simple.

on a side note: 300dpi is going to make grass and trees harsher than printing at 220 dpi so high DPI isn’t always better.

—

Cheers,
MacBook

In article ,
macbook <privaty please> wrote:

Never hit the resample option, this will give you the true size when you change the DPI value.
300 dpi is the standar among professional, it is overrated.
Most AM sheetfed and web press will downsample to 235-260 dpi. then you have FM printing on a press that could use more.

Presses do not downsample. They are not digital devices; they don’t take digital data.

The optimal resolution for imaging film to create a plat for a printing press is twice the frequency of the halftone that will be used on press. 300 pixels per inch is standard because the bulk of the printing that gets done is printed with a 150-line halftone.

For finer halftones, higher resolution is optimal. 350 pixels per inch is appropriate for 175-line halftones; 400 pixels per inch is appropriate for 200-line halftones.

—
Photography, kink, polyamory, shareware, and more: all at http://www.xeromag.com/franklin.html

On 2007-10-01 21:55:26 -0230, tacit said:

In article ,
macbook <privaty please> wrote:

Never hit the resample option, this will give you the true size when you change the DPI value.
300 dpi is the standar among professional, it is overrated.
Most AM sheetfed and web press will downsample to 235-260 dpi. then you have FM printing on a press that could use more.

Presses do not downsample. They are not digital devices; they don’t take digital data.

The optimal resolution for imaging film to create a plat for a printing press is twice the frequency of the halftone that will be used on press. 300 pixels per inch is standard because the bulk of the printing that gets done is printed with a 150-line halftone.

For finer halftones, higher resolution is optimal. 350 pixels per inch is appropriate for 175-line halftones; 400 pixels per inch is appropriate for 200-line halftones.

but they are digital devices. Unless you’re printing wih an old letterpress, then excuse me.
Digital Machines used: computer with Rip or imagesetter with RIP and now there’s platemakers with digital capability.

The RIP does resample digital data into spots and dots when it creates the halftone patterns that are set at the perimiters of the printed job. It even resamples vector art into spots (1200-2500) depending on what’s the best for the halftone screen and the paper/ink etc. Some presses are even digital right to the plate. Might have heard of them… they are called computer to plate or direct to plate. There’s even some that have direct to press ( right on the cylinder). It’s all digital until it outputs to film or the paper. It’s really quite interesting stuff if you go beyond the "how to books" and the experience of most agencies. Take it a bit further than easy.

The optimal resolution isn’t twice but 1.5 ( twice is just the standard used by ther bulk of graphic designers but it’s over compensating. 150 x 1.5 = 225 is the true optimal.

FM printing is it’s own beast but higher resolutions is usually better.

—

Cheers,
MacBook

In article ,
macbook <privaty please> wrote:

The RIP does resample digital data into spots and dots when it creates the halftone patterns that are set at the perimiters of the printed job. It even resamples vector art into spots (1200-2500)

Actually, these days most imagesetters are 3600 dpi. I’ve seen 2400 dpi imagesetters, but never 2500.

depending on
what’s the best for the halftone screen and the paper/ink etc. Some presses are even digital right to the plate. Might have heard of them… they are called computer to plate or direct to plate.

Yes. I service platesetters, among other things (I think that’s the term you’re looking for).

There’s
even some that have direct to press ( right on the cylinder). It’s all digital until it outputs to film or the paper. It’s really quite interesting stuff if you go beyond the "how to books" and the experience of most agencies. Take it a bit further than easy.
The optimal resolution isn’t twice but 1.5 ( twice is just the standard used by ther bulk of graphic designers but it’s over compensating. 150 x 1.5 = 225 is the true optimal.

Where do you get your information? Who told you that that is "best"? I ask because, you see, it contradicts everything currently known about data quantization.

—
Photography, kink, polyamory, shareware, and more: all at http://www.xeromag.com/franklin.html

On 2007-10-04 21:47:18 -0230, tacit said:

In article ,
macbook <privaty please> wrote:

The RIP does resample digital data into spots and dots when it creates the halftone patterns that are set at the perimiters of the printed job. It even resamples vector art into spots (1200-2500)

Actually, these days most imagesetters are 3600 dpi. I’ve seen 2400 dpi imagesetters, but never 2500.

You in North America or Europe? Different. 2450 / 2500 are pretty common but in different areas.

depending on
what’s the best for the halftone screen and the paper/ink etc. Some presses are even digital right to the plate. Might have heard of them… they are called computer to plate or direct to plate.

Yes. I service platesetters, among other things (I think that’s the term you’re looking for).

You got it, now the important part is to find out if
platesetters/imagesetters handle information digitally or analog. Once you answer that, you’ll be on your way to what my rebudle is all about. 🙂

There’s
even some that have direct to press ( right on the cylinder). It’s all digital until it outputs to film or the paper. It’s really quite interesting stuff if you go beyond the "how to books" and the experience of most agencies. Take it a bit further than easy.
The optimal resolution isn’t twice but 1.5 ( twice is just the standard used by ther bulk of graphic designers but it’s over compensating. 150 x 1.5 = 225 is the true optimal.

Where do you get your information? Who told you that that is "best"? I ask because, you see, it contradicts everything currently known about data quantization.

Maybe I should ask you the same. But the true answer is there is no true answer, This topic is not black and white, and most of us are in disagreement. (as we are ). For my part, I’ve tested this theory myself and will continue to preach what I’ve seen side by side comparisons. I’ve sent files to sheetfet and offset presses using various DPI, Color corrections and sharpness. Plus I’ve also tested what subjects look better with GCR or UCR seperations since most presses save money on GCR and will always notify you to use GCR. Of course GCR is safer, but it’s far from the best solution for quality on certain subjects. As far as DPI is concerned, 300 is MOST definetely over-compensating on many presses. YES, there are some new presses out (waterless) etc. that can handle higher DPI but most of them out there will still set there RIPs to under 150 LPI or less. This means that all your glorious images that you’ve sent at 300dpi will be stripped of some information when the RIP program calculated where to put the spots and halftone dots. In a matter of fact you could have send them 225 DPI and it would be the same.

If you don’t get this, it’s all o.k. It doesn’t make much of a difference. It would make a difference if you send files with the Resolution to low, but to high is quite alright. My issue is with the fact that you’ve stated that there is no resampling, in fact the RIP must resample in order to use the lower halftone setting. Or in other words, it drops information when this process happens.

This stuff is complex 🙂
—

Cheers,
MacBook