Hi Res Setting

[pixelpix]

how do I set my Canon T1 Rebel for very high res jpgs.  r/now only 72 res.  Thanks

[TCampbell · Accepted solution]

You may be thinking of DPI (72 dpi is a very common video "resolution"). DPI (sometimes called PPI) is an way to express the resolution of an image on a display or output media (such as printed output). There is no "DPI" until it's actually being displayed.

The camera itself doesn't have a concept of DPI (no camera does) because it's not an output device.... it's a imaging device. As such, it's "resolution" is the number of columns and rows of pixels on the sensor.

The T1i has a 15.5MP sensor with a resolution of 4752 x 3168. The sensor physically measures about 22mm x 15mm. If you were to think of that in terms of DPI, it'd be somewhere around 5000 dpi (roughly).

DPI on an output device depends on how large you display the output. A video display on has a specific pixel density -- so it's incapable of displaying more pixels per inch than it actually has. 72 dpi used to be a fairly common density. Printers, on the other hand, tend to have the ability to reach a fairly high DPI. But again... the DPI depends on how large of a print you plan to make. If you were to make a 4x6" print, your camera could support just about 800 dpi.

Ignore the value you see as "DPI" ... instead focus on the actual number of pixels you have and then decide how large the image is going to be when displayed -- keeping in mind that the output device may have a physical limitation with respect to it's own resolution (having nothing to do with the camera.)

[TCampbell · Accepted solution]

You may be thinking of DPI (72 dpi is a very common video "resolution"). DPI (sometimes called PPI) is an way to express the resolution of an image on a display or output media (such as printed output). There is no "DPI" until it's actually being displayed.

The camera itself doesn't have a concept of DPI (no camera does) because it's not an output device.... it's a imaging device. As such, it's "resolution" is the number of columns and rows of pixels on the sensor.

The T1i has a 15.5MP sensor with a resolution of 4752 x 3168. The sensor physically measures about 22mm x 15mm. If you were to think of that in terms of DPI, it'd be somewhere around 5000 dpi (roughly).

DPI on an output device depends on how large you display the output. A video display on has a specific pixel density -- so it's incapable of displaying more pixels per inch than it actually has. 72 dpi used to be a fairly common density. Printers, on the other hand, tend to have the ability to reach a fairly high DPI. But again... the DPI depends on how large of a print you plan to make. If you were to make a 4x6" print, your camera could support just about 800 dpi.

Ignore the value you see as "DPI" ... instead focus on the actual number of pixels you have and then decide how large the image is going to be when displayed -- keeping in mind that the output device may have a physical limitation with respect to it's own resolution (having nothing to do with the camera.)

[pixelpix · Accepted solution]

thank you so much, Tim. I had to read this 3 time to fully understand it but now I do. I am so glad I found this site.. Thanks again.

[ColinGlover]

You set the DPI in a photo editing software like Photoshop or elements when Editing or printing. You can resize DPI without changing the photo. When printing you choose the DPI you want. Magazines typically print at 300DPI. The higher the DPI the smaller the print will be. My 600d's 18 MP will give a 17inch print at 300DP!, which is acceptable. At 600 DPi 18 Mp will give you an8.5 inch print. Hope that helps.

[pixelpix]

Yes, Thank You!  That really helps.  To reiterate:  jpgs from my camera say 72dpi.  I change from 72 to 350 (and it gets much larger), do what I want to the colour, etc, then resize it back to 3.5 x 2 (business card size) and now have a 350 dpi business card size.........yes?  I just did this.........just want confirmation that it's truly a 350 dpi business card.  Thanks again

[TCampbell]

DPI tells the output device how large to show the image. Here's an example.

Your camera naturally as a 3:2 aspect ratio. Suppose you had a camera with a resolution of 300 pixels by 200 pixels (your real resolution is MUCH higher than that.) If you were to tell the software set it to 100 dpi and then print it, the print would come out 3" wide by 2" tall... because it's printing 100 pixels for each 1". If you changed it to 50 dpi, then it would come out 6" wide by 3" tall. It's the SAME 300 x 200 pixels... the difference is how tightly it's spacing them when the image is displayed.

In reality your camera is much much higher resolution and also your camera does not set a "dpi" to the image -- only computer software does that. Many programs will just default it to something. 72 dpi is the most common dpi used to display something on a computer screen. When printing, 300 dpi (or above) is considred to be high enough that most people will not be able to see the individual pixels when viewing from an average distance (even though most printers can print at much higher DPI settings.)