Image size is 240 PPI instead of 300 PPI

[burgermael]

when i go image size in photoshop, my images are always 240 pixels per inch but are 300 pixels per inch on my 7D Mark II. anyone know how to change this 

[TCampbell]

Ernie, please do not turn every thread into yet another argument.  As I stated in the last reply... the topic isn't related to the OP's question.  If you want to discuss it, it should be done in a different thread.

[ebiggs1]

"If you want to discuss it,..."

I don't, I simply made the connection of the two since both are non-existent issues.  There are more!

[CurtisEssen]

This is my first post here.

This is an old thread but I couldn't help but see how this discussion could confuse some people. It would have me if I were new to photography.

What your native raw image out of your camera is labled as is pretty inconsequential. Images from my 5DSr are labled 28.96 x 19.307 at 300 ppi when opened in photo shop from my browser. If you open it from Lightroom it will be whatever you told Lightroom to open it as in preferences. PPI does matter when resizing an image, say in photo shop. Go to image size and just change the ppi to 10 (I know that is absurd) but don't change the dimensions, keep them at say 28.96 x 19.307. Your image will shrink on the screen but right click it in maganify mode and choose print size. The image will return to take up the same screen space as before but will be very pixelated so in that sense it is not just a metadata lable and it should be very closly paid attention to when resizing for a certain print size or cropping. At this point close your file without saving it.

I hope this is helpful. I am Curtis Essen and you can see some of my images at [Removed link per forum guidelines]

[ebiggs1]

Perhaps you should re-read Tim Campbell's excellent reply.  There is no DPI or PPI in the camera.  DPI is a printer function.

"....  There are no pixels-per-inch (or DPI) in the camera... this is something that is only used when producing a physical print.

The camera sensor simply has some resolution.  ...

But lets use some easier numbers so you can visual this... suppose the camera resolution is 6000 pixels wide by 4000 pixels high.  ...

... the resolution simply is what it is.  But let's suppose you want to print this.  And you decide to set a PPI of 500.  Since the "I" in PPI and DPI is "inches" then 6000 ÷ 500 = 12 (inches) and 4000 ÷ 500 = 8 (inches).  So the output would produce an image which is 12" x 8".  

Suppose you change the DPI or PPI to 300.  Now it's 6000 ÷ 300 = 20 inches.  4000 ÷ 300 = 13.3 inches.  So you'd get an output which is 20" by 13 1/3rd inches.

You can set the DPI in Photoshop at will... but changing it doesn't actually DO anything to the image.   ... 

But for some reason... I still encounter people who seem to think it's really important to have that value set to some special number ... as if they just can't deal with the file if the value isn't set to that number.

Think of the DPI / PPI as a "coment field".  Nothing meaningful happens when you change it."

[CurtisEssen]

It is false to assume that the ppi does not affect the image quality either on screen or in the print. To say that ppi is just a comment field is very misleading. I just gave you a way to demonstrate that in my post. I do very large prints on a 44" Canon ipf8400 and have wallpaper prints floor to ceiling in our local hospital. Resolution and sharpness are very much affected by how you set your ppi when you resize an image.

[ebiggs1]

Right, you are talking prints.  Printers and prints have DPI cameras don't. DPI is set in software like Photoshop.

[CurtisEssen]

That is correct, but they affect each other. If your ppi is 300 but you set the dpi in your printer settings at 150 dpi you are going to have probably 4 pixels in each dot. If your print lab prints at 240 dpi it would make sense to set your ppi to 240. 1 pixel per dot. I know it gets more comlicated than that because pixels are mixed in a way to bring out the colors etc. If your photo lab feels they get the best results at a certain resolution why would you not believe them? You could send them a 300ppi image but if they print it at 240 dpi why send a larger file?

[Waddizzle]

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@CurtisEssen wrote:

That is correct, but they affect each other. If your ppi is 300 but you set the dpi in your printer settings at 150 dpi you are going to have probably 4 pixels in each dot. If your print lab prints at 240 dpi it would make sense to set your ppi to 240.

1 pixel per dot. I know it gets more comlicated than that because pixels are mixed in a way to bring out the colors etc. If your photo lab fe

els they get the best results at a certain resolution why would you not believe them? You could send them a 300ppi image but if they print it at 240 dpi why send a larger file?

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The concept of DPI, dots per inch, is fairly easy for most people to grasp.  It describes how a 6000 x 4000 file might be printed, to continue Tim’s analogy.  What is confusing is the concept of PPI, pixels per inch, which describes how the file might be “printed” to a visual display.  

Neither PPI and DPI are part of the EXIF metadata of a JPEG.  The EXIF contains “X Resolution” and “Y Resolution” fields.  DPI is a property associated primarily with hard copy printers.  PPI is a property associated primarily with visual displays.  But, both properties use the X and Y Resolution values, in conjunction with the overall X and Y dimension EXIF data to produce an output.  The X and Y Dimensions are used to describe the overall “canvas size” of the image.

You cannot change the pixel resolution of a monitor.  You can change the resolution of the signal sent to a monitor, but you cannot change the physical properties of it.  This is where PPI comes into play.  This is most readily apparent on larger, high resolution displays.  

Images can be displayed at their hard copy print resolution, at the resolution of their canvas size, or at a given crop factor..  These could be described as “page size”, “actual size”, or “scaled to fit.”

On my laptops with typical 1080P HD resolution, if I ask DPP, or LR, to display our 24MP image at 100%.  Typically, displaying at 100% means 1 pixel per dot.  I might see a portion of the image that is significantly less than half of the entire image.  If I switch to my 4K monitor, and display our 24MP image at 100%, then I might see significantly more than half of the entire image. 

[ebiggs1]

"It is false to assume that the ppi does not affect the image quality either on screen or in the print"

This depends on whether you have resample set to on or off.  PPI is the resolution of a digital image. PPI is used to resize images. DPI has nothing to do with anything displayed digitally!