Resolution In Photoshop

[Malek Agha]

If I want to print something out in 4k. What resolution do I need on photoshop? Will 72or 300 res matter? Also, this is being printed professionally.

 

[jsmithepa]

You go by the res of the output device, in this case the printer in question. 300 DPI is been pretty standard unless you have a super-duper printer I don't know about.

 

[Malek Agha]

You go by the res of the output device, in this case the printer in question. 300 DPI is been pretty standard unless you have a super-duper printer I don't know about.

I saw the difference between 72 res and 300 and 300 seemed skinnier for some reason.

 

[eodeo]

You're confused with the resolution and numbers you mention. 4k is "brute force" resolution. This is how much pixels the final image will have. No printer or other settings will change that.

On the other hand 72 or 300dpi measures how many pixels (dots) per inch are there. The fewer pixels per inch the bigger the printed image can be. For simplicity, we'll do only one axis - the 4k one. You'd take your 4k image and divide it by either 72 or 300. What you end up getting is either a) 55.5" print @ 72dpi or b)13.3" print- a physically much smaller print, but with higher detail level.

If you're familiar with apple's retina display it may help clear things further. 13.3" isn't inherently superior option. For start it's physically much smaller and such high detail (300dpi) would be wasted on all but the most sight gifted humans observing the said photo very closely. Human eye has a wall of how much detail it can distinguish and Apple's retina display tries to figure out how big the image (screen size) is going to be, and how far away a typical usage will be viewed from.

You should consult with your client, and if they don't know any better (which is very likely) I'd advise you to print both 72 and 300dpi version and check for yourself. 72 is a standard print since it looks really good. For high end print, really good isnt good enough so 300 or higher DPI is used. To print the same phyicaly large image at larger DPI, you'll need a lot more than 4k. In this example, for the 45.5" image @ 300 dpi you'd need (55.5x300)=17k image to start with. That means badass camera or (more likely) super huge 3d render, since I don't think you'll find many if any 17k image capable cameras.

 

[Malek Agha]

You're confused with the resolution and numbers you mention. 4k is "brute force" resolution. This is how much pixels the final image will have. No printer or other settings will change that.

On the other hand 72 or 300dpi measures how many pixels (dots) per inch are there. The fewer pixels per inch the bigger the printed image can be. For simplicity, we'll do only one axis - the 4k one. You'd take your 4k image and divide it by either 72 or 300. What you end up getting is either a) 55.5" print @ 72dpi or b)13.3" print- a physically much smaller print, but with higher detail level.

If you're familiar with apple's retina display it may help clear things further. 13.3" isn't inherently superior option. For start it's physically much smaller and such high detail (300dpi) would be wasted on all but the most sight gifted humans observing the said photo very closely. Human eye has a wall of how much detail it can distinguish and Apple's retina display tries to figure out how big the image (screen size) is going to be, and how far away a typical usage will be viewed from.

You should consult with your client, and if they don't know any better (which is very likely) I'd advise you to print both 72 and 300dpi version and check for yourself. 72 is a standard print since it looks really good. For high end print, really good isnt good enough so 300 or higher DPI is used. To print the same phyicaly large image at larger DPI, you'll need a lot more than 4k. In this example, for the 45.5" image @ 300 dpi you'd need (55.5x300)=17k image to start with. That means badass camera or (more likely) super huge 3d render, since I don't think you'll find many if any 17k image capable cameras.

I want to print a 30" by 36" image at 4k is 72 good enough?

 

[jsmithepa]

I saw the difference between 72 res and 300 and 300 seemed skinnier for some reason.

Don't understand what u mean by "skinnier" please use standard photographic terms. Of course when you have higher resolution, you will see more details, like when people complaint with HD, viewers are able to see the presenter's every zit and skin pores. In such cases, you may not want to show the greatest detail available. As the final "editor" it's your job to discern which is "better." It depends on the subject matter, the artistic presentation, the details captured from the original master.

 

[eodeo]

I want to print a 30" by 36" image at 4k is 72 good enough?

If by 4k, you mean the modern 4k versoin of 3840 pixels × 2160 (where 3.8k is somewhat close to 4 so it's called 4k) than yes. The lower value (2160) means that 30" image is just big enough to have 72dpi from that resolution.

 

[k1114]

If you know the size of the print then just go by that and 300dpi. You don't need to worry about the res which will be much higher than 4k. I would not suggest printing 72dpi, this will not look good.

 

[Solandri]

I want to print a 30" by 36" image at 4k is 72 good enough?

Those numbers are all related mathematically. You cannot just pick them at will.

"4k" is a 16:9 aspect ratio. 30"x36 is a 5:6 aspect ratio. If you force a 4k image to cover 30"x36", then yes the picture will have to be shrunk down in one direction (squares become rectangles, circles become ovals) to make it all fit. The things in the photo will look squashed, either skinny (squashed side-to-side) or fat (squashed top-to-bottom).

To print the 4k image at its original aspect ratio (squares stay square, circles stay circles), make sure "fit to page" is not selected when you print. On a 36" wide page, the math works out:

3840 pixels wide / 36 inches = 106.7 PPI
2160 pixels tall / 106.7 PPI = 20.24" tall

So if you print it at 106.7 PPI, the picture will cover the entire 36" width of the paper, but only span 20.24" of the 30" height. If it's centered on the page, there will be (30-20.24)/2 = 4.88" tall blank spaces above and below the picture.

If you print the 4k image at its original aspect ratio on a 30" wide page, then the math works out:

3840 pixels wide / 30 inches = 128 PPI
2160 pixels tall / 128 PPI = 16.88" tall

And the blank spaces above and below the picture will be (36 - 16.88)/2 = 9.56 inches tall.

Photoshop's resize command handles all of this seamlessly. You don't have to do any of the math.

• 
  ■If you start with the 4k image and resize its dimensions (i.e. inches), it will auto-adjust the DPI to the correct value.
  ■If you start with the 4k image and resize its DPI, it will auto-adjust the dimensions to the correct value.
  ■If you hold the dimensions constant and set the DPI, it will resample the image to fit, either increasing or decreasing the number of pixels.
  ■If you hold the DPI constant and set the dimensions, it will again resample the image.
  ■If you hold the dimensions constant and tell Photoshop to change the picture size in pixels, it will adjust the DPI to match.
  ■If you hold the DPI constant and tell Photoshop to change the picture's size in pixels, it will adjust the dimensions to match.

(PPI is conceptually identical to DPI, it differs for esoteric reasons important to printer and monitor manufacturers. I can get into it if you want to know, but for most Photoshop purposes you can use the terms interchangeably.)

• 
  ■For poster-size prints (36"x24") meant to be viewed from 5+ feet away, 72 PPI or better is usually good enough.
  ■For prints viewed from about 3 feet away, 150 PPI or better is usually good enough. This is typical for photos at gallery exhibitions.
  ■For prints viewed from 1-2 feet away, 300 PPI or better is recommended. This is typical for photos meant to be hand-held when viewed.