72 dpi to 300 dpi - can it be done?

Is it possible to take a 72 resolution image and bump it to 300 resolution and have a decent picture. Is there a trick to doing this?

dpi is meaningless when printing. You can have any dpi that you want (from 1 dpi to 10,000 dpi) and get the same quality print.

Rad

brain fart. I meant to say resolution and not dpi.

azpix wrote in post #3475533
brain fart. I meant to say resolution and not dpi.

OK, then I will change mine too:

resolution is meaningless when printing. You can have any resolution that you want (from 1 resolution to 10,000 resolution) and get the same quality print.

Rad

azpix wrote in post #3475300
Is it possible to take a 72 resolution image and bump it to 300 resolution and have a decent picture. Is there a trick to doing this?

> Open your image in photoshop.
> Goto Image -> Image Size
> Uncheck the box that says "Resample Image"
> Change the pulldown to "Inches"
> Adjust the resolution field to the desired resolution

You will see in the width and height text boxes the dimensions that your photo can be printed at the selected resolution. As you increase the resolution, the print size will decrease (more pixels per inch).

Good question pal and very good answers

What we need is a sticky about this up top of the board as this question or very similar regarding dpi workspace verses print resolution is asked every second day in the forum , Rad is like many of us , just sick and tired of going over the whole thing time and time again , its probably the most asked question in computer graphics , its amazing just how many people dont understand computer resolution .

Rod

thanks all for the answers.

burnt,
using your example, if you increase the dimensions after last step, your image quality will suffer I am assuming.

Resolution and DPI are NOT the same thing.

Resolution is well the resolution. How many pixels wide and tall.

DPI is the RATIO of those pixels to imperial, metric or other length measurements.


example:

4000 pixels wide. DPI of 72 = it prints 55.556 inches wide.
4000 pixels wide. DPI of 300 = it prints 13.33 inches wide.

The resolution has not changed. Only print size.

Now if you have an image that is 800 pixels wide and 72 DPI, you're screwed. It won't get much bigger than a 4x6 print.

azpix wrote in post #3476173
burnt,
using your example, if you increase the dimensions after last step, your image quality will suffer I am assuming.

Image quality will not be effected with the 'resample image' box unchecked. In fact, the image is exactly the same. When you start resampling, that's when you change the image quality.

DPI changes will not effect what you see on your screen, it only changes the print quality. For printing, you usually want your DPI around 200-300 for a good quality print. Any lower, and the print usually suffers, any higher and you don't even notice. If you change the DPI to 200 and photoshop says '4x6' ... then that's as large as you can print, you need a larger image.

cosworth wrote in post #3476212
Resolution is well the resolution. How many pixels wide and tall.

???

"How many pixels wide and tall" is just the image size, as measured in pixels.

RESOLUTION is pixel density. Any time you have a density, you have a ratio. In the case of a digital photograph, the ratio used to describe that density, or resolution, is pixels per inch (or centimeter, or whatever.)

Take a look at the following screen-cap:

MIME changed to 'text/html' | Content warning: data

Okay speaking as a former Imagery Analyst. Time to get the terms right....

"Resolution" is the ability to resolve an object at a certain size. For example a resolution of 1centimeter, means I can resolve that object are separate objects at at least 1 centimeter apart . If we want to get really really picky it is frequently rated in arc-seconds to remove distance from the equation.

What you are mostly talking about is "Image Size" or "Image Dimensions", which is the number of pixels per side in an image.

DPI, PPI is how many Dots or pixels per inch, in theory if printed.

So an image 3000x2400 pixels will have 10"x8" of print size at 300PPI at 100 DPI it will have 30"x24" print size. Normally though you will want to print at 240, 300 or 360 DPI depending on your printer. for display on the screen we usually use 72DPI pecause that is usually the resolution of the typical screen at one point (although not necessarily these days).

But presuming for the moment that I wanted to take a 300x240 pixel image (which would be a little of 1" square at 240DPI. I could probably take it up to 1200x960 pixels (or 5"x4" before it starts to degrade too much. But it really depends on the scene content if I could go more or not even that much before it becomes noticeable.

And before I forget, Adobe PS's use of the term resolution is incorrect and it really probably should more correctly be "pixel density"
Thanks for your patience,

For better ressampling use Lanczos, better than bicubic. My opinion.

Longwatcher wrote in post #3477312
"Resolution" is the ability to resolve an object at a certain size. For example a resolution of 1centimeter, means I can resolve that object are separate objects at at least 1 centimeter apart . If we want to get really really picky it is frequently rated in arc-seconds to remove distance from the equation.

Not to put too fine a point on it, but I always thought that that was "Resolving Power".

We use the term at work to describe the ability of an optical/sensor (or film) system [fancy way of saying "Camera"] to distinguish between two closely spaced items. The measurement we use is "Line Pairs per Millimeter". It is part of the weekly quality control that we have to do, so I use it a lot.

I believe that that is different from Image Resolution, which is what I was talking about.

Rad

azpix wrote in post #3475300
Is it possible to take a 72 resolution image and bump it to 300 resolution and have a decent picture. Is there a trick to doing this?

Yes there is a way but decent.....thats a maybe. But in Scott Kelby's book Photoshop CS2 for Digital Phototgraphers he talks about a way of increasing the size of your images to print bigger by checking resample and using Bicubic Smooth or Bicubic Sharp i cant remember which one it was but once you try both you can tell which one is the right one. But when you go bigger you do start to lose image quality in a sense. Basically your adding information(pixels) that wasn't there to begin with.