DPI in photoshop

[Nataq]

Im seeing here and there to create the art at 300 dpi. Is it set in the image menu then image size and then where it says resolution ? There I have only 100 (if it is what dpi is) and it says pixels/inch (I worked with inches everywhere). So am I getting that right ? I tried changing this to 300 and that bring the image a lot bigger even if widht and weight are still showing the same. Like it is right now (that setting at 100) gives me the right size on screen and even maximized at 100% image still looking decent. So what am I missing here ??

[Impactor]

first off - set your size (dont confuse res) - let say u want it 10x10 cm (work with measurements, not pixels)

then select 300-350dpi (dots per inch)

[RayB]

How it looks on-screen is irrelevant. Your screen is made up of certain size pixels. Ink on paper needs to use smaller dots to look good.

The least confusing way to fix this would be to do this:

1. Create a NEW document. In the new doc settings, choose the following:

 A. Set the Resolution first. Set it to 300. And in the drop down next to that, select "pixels/inch".
 B. Now you can set the size above that. Make sure you have select inches. Enter in the correct width and height in inches.
 C. Choose RGB, 8bit.

[Nataq]

What im not getting is that its not written DPI on my screen. It says resolution. So thats the same thing ?

If I just change the resolution to 300 instead of 100 it actually bring the image bigger and I cannot see loss of quality even at 100% size. Question is: resolution = dpi

[RayB]

What im not getting is that its not written DPI on my screen. It says resolution. So thats the same thing ?

Sorry, yes, I meant "Resolution" (message editted to say that now).

If I just change the resolution to 300 instead of 100 it actually bring the image bigger and I cannot see loss of quality even at 100% size. Question is: resolution = dpi

The reason I suggested starting with a new document is that some people get mixed up with a couple options that PS has when you resize an image's resolution. There is an option call "Resample Image". If you do not have that checked on, then PS does not change your actual graphics. All it does is set the document settings to "300" dpi which only affects printing.

If you don't understand this, do a test. Print your 100dpi image on your regular printer. Then change the resolution to 300, with Resample Image NOT checked on. In PS your image will look the same n your monitor. Now print it out again. You will see it prints out 3 times smaller than it did before. That's because the printer is now cramming in 300 pixels per inch.

So, you need to check on Resample Image, set the res to 300, THEN go in the document size and set it to the correct width and height in inches.

PS will then stretch the graphics to fit the correct size.

[Nataq]

Ok, when you say this:

There is an option call "Resample Image". If you do not have that checked on, then PS does not change your actual graphics. All it does is set the document settings to "300" dpi which only affects printing.

Isnt all that we need ? Not changing graphics and bring the print better (to 300 dpi). Why all that manipulation then ? Sorry but im still confused. The size of the image is not altered at any point if we dont change the widht and height isnt that right ? So why cant we just change the resolution only ? Or is it that because of resolution the image size is not necessarly the size showing by the widht and depth.  Or may I say it this way: even if widht and height are the same if you print a square on a sheet with different resolution then the square wont be the same dimension ?

And if we forget all of this, I did bring the resolution from 100 to 300 for my marquee and when looking at it zoomed 100% it still looks perfectly fine, that mean I am OK and I can forget about all of this ?

[Nataq]

Ok Ive done some testing and its true that PS doesnt change anything if resample image is not checked and if I increase the resolution to 300. So just like this it would be good to print ?

Sorry if I sound like a complete retard! hehehe!

[RayB]

You ignored a key point of my post: PRINT OUT A SAMPLE at each resolution! That will help you picture what is happening. Relying on the version you see on the monitor won't help because, as you said, it looks the same.

Let's say you have an image that is 300 pixels x 300 pixels and the resolution is 100 pixels per inch. What size do you think it will print out? (hint: 100 pixels in every inch-- Answer: Your image will physically be 3 inches by 3 inches when printed on paper.  300 pixels divided by 100 = 3).

Change the resolution to 300, with no resampling. Image on monitor will look the exact same (because your monitor pixels don't change size). Print it out. What size will the physical printing be? (hint: 300 pixels in an inch this time. Your 300 pixel by 300 pixel image will print out 3 times smaller because the printer is instructed to use 300 pixels for every inch instead of 100.

[Nataq]

Ok thank you for all the explaination. Ill have to do some print test now