DPI for printing ?

Is 300 DPI the best for printing photographs, or the more the better? Thanks

Some believe, and has become a standard of belief, that you need 300dpi for a print to be 'good enough'.
Think about modern cameras with, one with 5500 pixels x 3700 pixels, for example.
Printed to 4x6 print it has over 900 pixels per inch!
Printed to 8x12 print, it has over 450 pixels per inch!

If you look at 4x6 vs. looking at 8x12, can you really say the smaller print 'looks better'...it has more dpi?!
The human eye simply is limited in its abilty to even detect ONE pixel from another, when the pixel is too small.
Enlarge the same image to 40x60, and you CAN see individual pixels from 10" away, but not from 10' away.

300 dpi is a good general guideline for those that don’t want to get into the technical details of size and viewing distances. It is just a guideline though.

Dpi is dots per inch, you should be looking at pixels per inch. DPI is a printer resolution term that gets interchanged.

gonzogolf wrote in post #19232114
Dpi is dots per inch, you should be looking at pixels per inch. DPI is a printer resolution term that gets interchanged.

Yup, you might print at 1000 dpi, but in that 1000 dots you may be reproducing only 150 pixels.

One is input and the 300ppi is a good rule of thumb for that. It depends on viewing distance however. I can tell you I have printed 13x19 at 150 ppi and it looks just fine at a normal viewing distance.

gonzogolf wrote in post #19232114
Dpi is dots per inch, you should be looking at pixels per inch. DPI is a printer resolution term that gets interchanged.

Yes, 'dot per inch' of INK vs. 'pixel per inch' is very confused, even by commercial printers of photos!

1. Understand that your typical inkjet printer lays 4800 or 9600 DOTS of INK PER INCH on paper...therefor spec of 300 dpi is obviously meaningless in the context of inkjet printing
   
2. In the world of catalogs or newsprint, DOTS PER INCH of INK does have meaning, in the sense that photos on catalogs or newsprint have a direct effect on quality of reproduction, tottally INDEPENDENT of whether the JPG photo was made of 600 pixels per inch or 300 pixels per inch! Next time, look at a photo in the newspaper vs. a photo in something like National Geographic.
   
3. Often commercial printing services demand "300 dpi" (3000 pixels to fit within a 10" print) when they REALLY mean PIXELS per inch, not DOTS per inch.
   

Thanks for your input guys...I gotta admit, I didn't understand the DPI/PPI conundrum, and I thought they meant the same. I wonder what Canon DPP means when it asks for Output resolution then:

Lightroom does that too. Both are using 'dpi' when it really means PIXELS per inch!

When you tell LR to output 20" x 30" JPG at '300dpi', it creates 6000 x 9000 pixels in the output file.

Seemingly programmers who do not fully understand photography or photographic printing.
I believe the issue is that they also make files to be used by offset printers, and they need to embed into the EXIF that the offset press should mimic '300 dot per inch halftone screens' used for photo printing decades ago. (My speculartion, not confirmed.)

Wilt if you hadn't replied with the halftone screen information, I would have. Again though only my surmise, and not confirmed.

The value that is set in the EXIF DPI/PPI tag is also mostly meaningless. Until you send the image to software that is offset press printing aware. I have done some DTP work in Adobe InDesign and that can be very frustrating when the DPI/PPI is set to values that are not 300. The worst is when it's set to 72. All of a sudden you have a 1200px wide image filling 16" of page width, instead of 4".

Alan

strobe monkey wrote in post #19231934
Is 300 DPI the best for printing photographs, or the more the better? Thanks

Assuming you use a print lab rather then home DIY printing, you should ask the lab what they prefer. They're the ones who know the capabilities of their printers or presses. The answer also depends on what you're printing for. A 12x18 print that hangs on your wall requires a much different resolution than a billboard that is 30x10 feet, or a mural that is 12x12 feet. Viewing distance also affects the required resolution. A print that will be viewed from a distance of 18 inches needs a higher ppi than one that will be viewed from a distance of 18 feet.

BigAl007 wrote in post #19232219
Wilt if you hadn't replied with the halftone screen information, I would have. Again though only my surmise, and not confirmed.

The value that is set in the EXIF DPI/PPI tag is also mostly meaningless. Until you send the image to software that is offset press printing aware. I have done some DTP work in Adobe InDesign and that can be very frustrating when the DPI/PPI is set to values that are not 300. The worst is when it's set to 72. All of a sudden you have a 1200px wide image filling 16" of page width, instead of 4".

Alan

Which makes it especially puzzling when you find that '72' is the DEFAULT value inserted by the program!

Wilt wrote in post #19232192
Lightroom does that too. Both are using 'dpi' when it really means PIXELS per inch!

When you tell LR to output 20" x 30" JPG at '300dpi', it creates 6000 x 9000 pixels in the output file.

Seemingly programmers who do not fully understand photography or photographic printing.
I believe the issue is that they also make files to be used by offset printers, and they need to embed into the EXIF that the offset press should mimic '300 dot per inch halftone screens' used for photo printing decades ago. (My speculartion, not confirmed.)

I use 300 DPI and also check resize (to 2800 pixels on long side). LR generates 2800 pixels on long side, not 9000.

I specified print size in Inches AND I specified that I wanted 300dpi, and it gave me Inches * 300 pixels as each axis output.
That is how I made two 12" x 60" canvas wall prints from two 12MPixel Canon S110 images, shot when I was too lazy to want to carry dSLR around all day while walking!

In comparison, YOU asked for 2800 pixels, so that is what it gave you, ignoring the '300dpi' except to embed that value in the EXIF.

Dots per inch is simply a way to translate the dimensions of a computerized image (in pixels) into a physical size like a print (in inches). In that sense, you are basically saying, I want X pixels in the computer image to occupy an inch on a printed document. The more explicitly correct term is probably "pixels per inch" or PPI. DPI is probably more a holdover in terminology from halftone screen printing and similar techniques.

For inkjet and contone printing, how the physical matrix of ink gets laid down by the printer is not embodied in this dimension explicitly. You are not telling the printer how to lay down the droplets of ink, you are simply defining a physical size of the print. The printer can figure out how to lay down the ink (the D's per I). Typically, the print driver will have "quality" settings that let you define the density of the ink in the printed image, and that is a measure of how the printer lays down the ink in DPI; however, this is not what you are defining when you tag a file with the "DPI" (PPI) tag.

Some folks might tell you things like "Epson printers like the image file to be at least 360 dpi" or something like that. That may be true. There may be physical reasons for a specified DPI (PPI) sent to a specific printer, based on the algorithm used by the printer driver, or the density of nozzles on the inkjet print head - this is something that you would have to research for your specific printer to get a sense of whether or not there is an optimal print resolution, in DPI (PPI), to use for YOUR printer.

For example:

http://www.gballard.ne​t/psd/sharpening.html

Also, "DPI" (PPI) is simply a tag contained in the file's metadata. It permits the user of the file to specify how big the physical print should be based on the image's pixel dimensions. A 6000 x 4000 pixel image tagged with 300 dpi has the exact same amount of pixels as a 6000 x 4000 pixel image tagged with 150 dpi, or 1600 dpi. The only difference will be the physical size (in inches) of the printed output. Now, obviously, this will affect the quality of the print - a huge dpi tag will make a tiny printed image and a really small dpi tag will make a huge print that potentially has big blocky areas for each pixel. However, that might be just fine for a billboard, where the viewing distance is hundreds of feet away.

You can test the balance between PPI and printer quality settings to optimize your print for a specific viewing distance (the "viewing distance" is roughly something close to 2x the diagonal length of the print). Most times, you are trying to squeeze out the largest print you can make with the given amount of pixels in an image, without having to resort to uprezing the image and making up new pixels to increase the pixel dimensions of the image. In other words, how low in PPI (i.e., how big in physical dimensions) can I print with the number of pixels I have in my source image before I notice a drop in print quality for a particular viewing distance? If the intended viewing distance is 12 inches (which is sort of ludicrous) for a 24 inch print, you may need to print at a pretty high PPI and not have enough pixels, but you may have enough pixels with the same exact image file to print a billboard, with a significantly huge viewing distance and much lower PPI requirement.

See: http://resources.print​handbook.com …/viewing-distance-dpi.php

for example.

It is up to you to figure out what PPI you can get away with and still retain the output quality you want, particularly for the intended viewing distance. There are other factors in printing, such as the paper type, that will also affect these settings, so you need to experiment and test before coming up with a specific number or set of values.

Kirk

So, if I understand it correctly, I have to specify maximum print size and DPI for the export of final image. Is limiting of the file size going to affect it? I limit to 2500 Kb.