What's the impact of "Resolution"-values?

[designamite]

Hi guys,

I really love the sharpness/high quality of images and now I got a MacBook Retina I can see the details even more. I was wondering when starting a "New file", if the values of "Resolution" has an impact on the eventual quality of the image? If so, what are the best values to put here?

Looking forward to your replies, please help me get a better understanding of this.

 

[Tom Mann]

There are a couple of ways to think about this, but, if done correctly, they will be equivalent.

My approach is to first figure out the largest final size of the image in real world units (ie, inches, cm, etc.), and then, assuming you are not making posters or billboards, set PS's "resolution", ie, "ppi" (pixels per inch) to 300. The product of these two numbers gives you the pixel dimensions of the image.

For example, if you want to make a 10 inch square image, when you multiply 10" by 300 ppi, you get that the dimensions of the image in pixels should be 3000 x 3000 or larger.

Going higher in ppi, will only make minor improvements to any picture of this size or smaller, and these will only become visible if you make a lot of changes to the image.

You might be able to get away with a smaller value of the ppi, say, down as low as 200 ppi (...and hence, an image with smaller pixel dimensions), but a lot depends on the image, the reproduction method, the viewing distance, etc.

In contrast, if you are going to put the image on the web, the only thing that matters are the pixel dimensions of the image. In this case, the ppi (aka, Adobe's "resolution" number) is completely ignored. You simply need to size it to fit the space on the web page where it is going.

HTH,

Tom M

 

[Tom Mann]

BTW, there are some odd things about specific reproduction methods like commercial offset / halftone printing, as well as particular displays such as the Retina, but let's get through the basics first before we discuss these.

T

 

[MikeMc]

One comment.....What you do for the web and for printing are different...always remember where your image is going.

That said I always try to get the largest, sharpest highest resolution possible......But that's me, as I like the prints....

 

[ALB68]

If you are going to the web with your images, 72 or 96 is common. Also, as Mike points out always be aware of your end use. That 1000 pixel image at 72ppi is 13.8" wide in physical size.(1000/72=13.888). Convention is to print at 300ppi so if you resize this to 300ppi, then the physical print size drops to 3.33".
Then the discussion begins. Why can't I just print it like it is..well..you can, and in many cases it may be just fine and look OK to you. Here is a pretty good article that goes into a pretty good explanation of all this, which can be quite confusing.
http://www.htmlgoodies.com/tutorials/web_graphics/the-resolutions-too-low-printing-web-graphics.html

 

[designamite]

There are a couple of ways to think about this, but, if done correctly, they will be equivalent.

My approach is to first figure out the largest final size of the image in real world units (ie, inches, cm, etc.), and then, assuming you are not making posters or billboards, set PS's "resolution", ie, "ppi" (pixels per inch) to 300. The product of these two numbers gives you the pixel dimensions of the image.

For example, if you want to make a 10 inch square image, when you multiply 10" by 300 ppi, you get that the dimensions of the image in pixels should be 3000 x 3000 or larger.

Going higher in ppi, will only make minor improvements to any picture of this size or smaller, and these will only become visible if you make a lot of changes to the image.

You might be able to get away with a smaller value of the ppi, say, down as low as 200 ppi (...and hence, an image with smaller pixel dimensions), but a lot depends on the image, the reproduction method, the viewing distance, etc.

In contrast, if you are going to put the image on the web, the only thing that matters are the pixel dimensions of the image. In this case, the ppi (aka, Adobe's "resolution" number) is completely ignored. You simply need to size it to fit the space on the web page where it is going.

HTH,

Tom M

Thanks for your reply. If I understand correctly, you're saying entering 300 as Resolution-value gives good quality. I've tried it and the image indeed looks sharp/high quality to the eye.

 

[designamite]

One comment.....What you do for the web and for printing are different...always remember where your image is going.

That said I always try to get the largest, sharpest highest resolution possible......But that's me, as I like the prints....

I understand. But when creating f.e. a logo, which you eventually want to use on both (printing and web), what's the best resolution-value to go with?

 

[designamite]

Basically, I'd like to know what the best "resolution"-value is to start a design with. To make sure that we're talking about the same thing, I've attached this screenshot.

 

[MrToM]

Hi designamite,

In the absence of the other guys I'll try and continue their excellent advice so far...

It looks like you've grasped that when using images for web "resolution" makes not one jot of difference....and when printing images on a printer it controls the output size of the print......I think that's already been established.

Its not always possible to know what an image is going to be ultimately used for so I usually err on the side of caution and set the "resolution" to 300 each and every time....regardless. (And thats in PPI not PPCM)

Whilst working in PS it has no effect whatsoever on the output.
That said, it can and is used when, you re-sample the image or start a new document to a specific output (print) size. As re-sampling is generally regarded a big no-no you could even rule out re-sampling as well.
(It pops up whilst using the 'crop' tool too but I wouldn't recommended using it there.)

For instance if your job requires a photo-sized 10" x 6" print.....ultimately.....then you can use that panel to enter those values, in inches and the resolution, (300), and the amount of pixels you need for that image are automatically calculated for you.

An image can never really be "too large":
If you need to output to the web then using "Save for Web..." allows you to output to specific pixel dimensions.
If you need to print the image you can just increase the dpi.....at least if you start with the recommended minimum of 300 you'll never go below it.

I always aim to work on as big an image as possible......using "Save for Web..." to optimize the image as required.
This does actually re-sample the image but in a 'reduction' manner, which is slightly less frowned upon than re-sampling up.
Only your system limits you as to how big an image you can work on.....so work on a big image and then adjust as needed when you need to......'big to small' is much better than 'small to big.'

I don't use a Mac but in answer to your original question, no, resolution has no impact on the eventual quality of an image.

Hopefully that hasn't confused you further but it really is just a simple balancing act between the pixels dimensions, resolution and output size....and if you never print the image then you can even forget about the output size too.

Regards.
MrTom.

 

[designamite]

Hi designamite,

In the absence of the other guys I'll try and continue their excellent advice so far...

It looks like you've grasped that when using images for web "resolution" makes not one jot of difference....and when printing images on a printer it controls the output size of the print......I think that's already been established.

Its not always possible to know what an image is going to be ultimately used for so I usually err on the side of caution and set the "resolution" to 300 each and every time....regardless. (And thats in PPI not PPCM)

Whilst working in PS it has no effect whatsoever on the output.
That said, it can and is used when, you re-sample the image or start a new document to a specific output (print) size. As re-sampling is generally regarded a big no-no you could even rule out re-sampling as well.
(It pops up whilst using the 'crop' tool too but I wouldn't recommended using it there.)

For instance if your job requires a photo-sized 10" x 6" print.....ultimately.....then you can use that panel to enter those values, in inches and the resolution, (300), and the amount of pixels you need for that image are automatically calculated for you.

An image can never really be "too large":
If you need to output to the web then using "Save for Web..." allows you to output to specific pixel dimensions.
If you need to print the image you can just increase the dpi.....at least if you start with the recommended minimum of 300 you'll never go below it.

I always aim to work on as big an image as possible......using "Save for Web..." to optimize the image as required.
This does actually re-sample the image but in a 'reduction' manner, which is slightly less frowned upon than re-sampling up.
Only your system limits you as to how big an image you can work on.....so work on a big image and then adjust as needed when you need to......'big to small' is much better than 'small to big.'

I don't use a Mac but in answer to your original question, no, resolution has no impact on the eventual quality of an image.

Hopefully that hasn't confused you further but it really is just a simple balancing act between the pixels dimensions, resolution and output size....and if you never print the image then you can even forget about the output size too.

Regards.
MrTom.

Thanks for your reply. Oh wow, overall it sounds very complicated to me haha. But thanks for clearing it up that the resolution has no impact on the eventual quality of an image.

 

[MrToM]

No worries.

Its one of those things that on paper does look really complex, but in practice is just simple maths....A*B = C...or any combination thereof.

Just create a new document, 300 x 300px and with a resolution of 300 ppi (dpi as PS likes to call it).
Fill it with something like an image or whatever.
VIEW @ 100%.
Then go to Image > Image Size... UNCHECK "resample"
Change the "Width" and "Height" values to read in Inches.....they should both be 1. (300 pixels per inch, image is 300px wide therefore it would print a 1" square)

Change the "Resolution" to something ridiculous like 1000
Note the "Width" and "Height" size will change dramatically. (In inches)
Click OK out of it and check your image.......any different? (It shouldn't be)

Now check the "Print Size..."
View > Print Size...
The image should be very small because of the higher ppi.

Change the ppi back to 300 and then View > Print Size again....the image should now be much bigger.

Note that in both cases the amount of pixels has not changed.....its still 300x300px...but the Output (Or Print Size) changes significantly.

That example demonstrates you can change the output size using the ppi......and constant pixel dimensions.
You can also keep the ppi constant and have the amount of pixels change.......check "re-sample" and you'll see.

Regards.
MrTom.

 

[Tom Mann]

designamite - It would help if you gave us some context for your question. Can you give us an example of exactly what are you trying to do, e.g., "I want to add a caption to an existing (scanned) photo.", "I am mostly interested in doing graphic designs starting from a blank canvas", etc. etc.

Thanks,

Tom M

 

[ALB68]

Gentlemen,
All of your information is well received by the OP but please your overwhelming him with information.
Simple answer : 300ppi

 

[designamite]

Thank you all! I feel I've got a better understanding about the settings right now.
@Tom Mann: Basically, doing graphic designs starting from a blank canvas

One more question, @MrTom emphasised on "pixels per inch, not pixels per centimeter". What's the difference between that (besides it's a different measure-tool) ? Because I mainly start with blank canvas based on centimeter x centimeter.

 

[ALB68]

Thank you all! I feel I've got a better understanding about the settings right now.
@Tom Mann: Basically, doing graphic designs starting from a blank canvas

One more question, @MrTom emphasised on "pixels per inch, not pixels per centimeter". What's the difference between that (besides it's a different measure-tool) ? Because I mainly start with blank canvas based on centimeter x centimeter.

300ppi = 118.11 ppc There is an option in the PS Image size panel for both.

 

[MrToM]

...One more question, @MrTom emphasised on "pixels per inch, not pixels per centimeter". What's the difference between that...

I mentioned PPI for 2 reasons:

1. Habit / consistency.
When setting the resolution of a digital image, PPI, (Or erroneously DPI), is the more usual ratio to use, its rare to use PPCM / DPCM.
Not only that but the primary output device used will probably be a pixel based device, an LCD monitor, which are also usually quoted as having resolutions in PPI.

2. The Standards Institute.
In the UK we follow the SI when it comes to units for measurement.
That means for the Imperial system we use Miles, Feet and Inches.
The metric system uses Kilometers, Meters and Millimeters.

We shouldn't, but do, use 'centimeters' for linear measurement......in much the same way that we don't use 'decimeters' either.

I guess it just comes down to what you feel comfortable with and whether or not you want to stick with 'tradition'.

Regards.
MrTom.

 

[ALB68]

I mentioned PPI for 2 reasons:

1. Habit / consistency.
When setting the resolution of a digital image, PPI, (Or erroneously DPI), is the more usual ratio to use, its rare to use PPCM / DPCM.
Not only that but the primary output device used will probably be a pixel based device, an LCD monitor, which are also usually quoted as having resolutions in PPI.

2. The Standards Institute.
In the UK we follow the SI when it comes to units for measurement.
That means for the Imperial system we use Miles, Feet and Inches.
The metric system uses Kilometers, Meters and Millimeters.

We shouldn't, but do, use 'centimeters' for linear measurement......in much the same way that we don't use 'decimeters' either.

I guess it just comes down to what you feel comfortable with and whether or not you want to stick with 'tradition'.

Regards.
MrTom.

But setting either one is going to yield the same results is it not? I have to admit that I grew up in the US when the metric system was rarely used. But, that's other thread material.

 

[Tom Mann]

But setting either one is going to yield the same results is it not? ....

Or, nothing at all if the image is destined to go on the web, LOL.

Tom M