When I take a picture with my digital camera in a format for example of 2832x2128. Isn?t it true that at this point the picture is just a series of horizontal pixels times the vertical pixels and the concept of dpi comes into play only when you are looking at the picture on a medium such as a monitor (72dpi) or printed photo (300dpi). So until it is observed on a medium there is no such value of dpi assigned to the jpg photo. Is that true??
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Those Pesky Pixels
- Thread starter brook
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see my answer in the "new" forum.
A puter can only remember ones and zeros, on and offs. So to remember something like a photograph, it needs to be chopped into little pieces calles "picture elements" or "pixels". Indeed: you get something like a mosaic or a grid, and the puter can remember that the fifth element on the seventh line should have these specific intensities of red, green and blue light to build up the colour needed.
(Vectors are another approach, but that's beyond the scope of your question).
A puter can only remember ones and zeros, on and offs. So to remember something like a photograph, it needs to be chopped into little pieces calles "picture elements" or "pixels". Indeed: you get something like a mosaic or a grid, and the puter can remember that the fifth element on the seventh line should have these specific intensities of red, green and blue light to build up the colour needed.
(Vectors are another approach, but that's beyond the scope of your question).
brook... go back to your original question http://www.photoshopgurus.info/forum/viewtopic.php?t=2917 and you will find the answer! 
Again, 72 ppi (forget the dpi) is the "standard" resolution for digital cameras. Yes, you and your friends can increase the ppi, but you will have to decrease the image size to do so!
Again, 72 ppi (forget the dpi) is the "standard" resolution for digital cameras. Yes, you and your friends can increase the ppi, but you will have to decrease the image size to do so!
Thanks, great explanation. I didn't read your other post yet so thanks for pointing me to it. I looked all over the web but you're the only one who finally said the magic words "72 ppi is the STANDARD resolution for digital cameras", thank you.
My digital camera manual (fugi finepix 6900) doesn't even mention 72 ppi or how to change it to other higher resolutions. It only tells about the width and height from various megapixel settings, i.e. 3M gives you 2048 x 1536.
My digital camera manual (fugi finepix 6900) doesn't even mention 72 ppi or how to change it to other higher resolutions. It only tells about the width and height from various megapixel settings, i.e. 3M gives you 2048 x 1536.
MindBender
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Your original supposition is basically correct. If you look at the acronym DPI... dots per inch. Right after you take a picture all you have is the "dots" portion... the pixels. There are no measurments imposed on the image until you need to deal with something that uses inches... most commonly a printer. The "standard dpi" of 72 is simply imposed on the image because when it goes into the computer, it will need that information if you were want to print it or open it in photoshop or something. It doesn't make any difference because you are simply dealing with a finite number of pixels. So if you have 72 pixels wide at 72dpi it would be... one inch. If you had an image 1280 pixels wide at 72dpi it would be about 17 inches. The actual pixels are what determine how much actual data is recorded into that "grid". The DPI is just used for output.
Hope that didn't ramble too much ...$0.02 :B
Hope that didn't ramble too much ...$0.02 :B
sPECtre
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Yes, to echo MB there is no resolution on a digital camera file , the image editing program attribute 72dpi by default (see the other thread for the why)
-in fact the only resolution could be the one of the sensor (divide the number of pixels by the sensor size) but even with that, the camera electronics sometimes makes an interpolation to give a given amount of pixels...
-in fact the only resolution could be the one of the sensor (divide the number of pixels by the sensor size) but even with that, the camera electronics sometimes makes an interpolation to give a given amount of pixels...
I believe digital camera images are tagged 72 dpi (ppi) since that is the common monitor resolution. The EXIF header tags it at the time of exposure. Most photographers I know shoot at the highest possible camera setting (5 meg. +) so they have as many pixels as possible to work with.
So when I take a digital picture I basically have a grid (or mosaic as Erik says) of pixels horizontal times vertical. If I view those pixels on a 72 ppi (or dpi) monitor then it would default to 72. What if the resolution of my monitor was 96 ppi? I guess the image resolution would default to 96 ppi. Can somebody tell me how to get those pesky pixels to the printer with the least amount of damage to the pixels? Is it better to size them in the PS Image Size dialog box or should I just go to the printing software properties for my HP printer and select "best" output? This is assuming I'm not making any changes to the size of the photo and I'm printing at a 1:1 ratio.
On one hand you have your monitor. That's where you see your image displayed. That monitor is controlled by your operating system and your video card driver.These can be set at different screen resolutions like for example 640x480, 800x600, 1600x1200,...depending on your monitor's specs and your vidcard drivers options.
Say you set this at 800x600. Then this means that you will be able to see, at full screen!, an image of 800pix wide, and 600 high.
On the other hand, your monitor is said to display 72 pixels per inch, or 96 if one is to believe Microsoft. This was/is important as you get a realsize view at this setting. An image at 300dpi will be much larger on your monitor then when printed. And image at say 50 ppi will be smaller.
Best is to experiment and try this out. Say you want to print a 5x4 inch pic. At 72 you need 360x288pixels (you're with me here?), and at 96 you need 480x384 pixels. Now take a ruler and measure on your monitor which one is correct: 360x288, or 480x384.
Apart from this, this has no importance at all as your monitor only displays a number of pixels. It's only to get an idea of the printing size that you can use the 72/96 setting.
Say you set this at 800x600. Then this means that you will be able to see, at full screen!, an image of 800pix wide, and 600 high.
On the other hand, your monitor is said to display 72 pixels per inch, or 96 if one is to believe Microsoft. This was/is important as you get a realsize view at this setting. An image at 300dpi will be much larger on your monitor then when printed. And image at say 50 ppi will be smaller.
Best is to experiment and try this out. Say you want to print a 5x4 inch pic. At 72 you need 360x288pixels (you're with me here?), and at 96 you need 480x384 pixels. Now take a ruler and measure on your monitor which one is correct: 360x288, or 480x384.
Apart from this, this has no importance at all as your monitor only displays a number of pixels. It's only to get an idea of the printing size that you can use the 72/96 setting.
Dont mean to belabor this but not sure I even follow that.
A monitor renders the image in a PPI mode. Since that is all a monitor has is pixels. Opening a 72 ppi tagged image from a digital camera will (depending on the preset camera resolution) present a very large "print" size.
Printers work on DPI principle. Dots of ink per inch. Excluding real high end printers, using 240-300 dpi is a good resolution size for the print heads to yeild a satisfactory print.
Once you have resized the image for resolution, you set the final print size (5x7 8x10 etc.) you are looking to hang in your art gallery.
When you open an image from a digital camera in PS, it'll be opened at 72ppi because that happens to be what the (mac) monitor displays per inch. Photoshop cannot even take the resolution into account when it comes to displaying images on the monitor as it is the operating system that is in control.
If your file is 7200 pixels wide, it'll probably not fit on your monitor (not on mine anyway). If it is loaded as 72 ppi, you will get the size it will be printed when you don't change the resolution and hit Cmd/Ctrl+P. For PC, it will be a bit different as PC monitors are supposed to be 96ppi.
If you change the resolution to 300ppi, it will have the same size on your monitor, as on the screen only the number of pixels count. But, when printed, the result will be more than four times smaller than what you see on your screen. So you can use changing the resolution to get a better quality print, but it will inevitably be smaller, which can be your intention.
If, and only if, you uncheck the resample checkbox.
If your file is 7200 pixels wide, it'll probably not fit on your monitor (not on mine anyway). If it is loaded as 72 ppi, you will get the size it will be printed when you don't change the resolution and hit Cmd/Ctrl+P. For PC, it will be a bit different as PC monitors are supposed to be 96ppi.
If you change the resolution to 300ppi, it will have the same size on your monitor, as on the screen only the number of pixels count. But, when printed, the result will be more than four times smaller than what you see on your screen. So you can use changing the resolution to get a better quality print, but it will inevitably be smaller, which can be your intention.
If, and only if, you uncheck the resample checkbox.