image quality

[seniornewbie]

I know Im not understanding some basic things so Ill ask. I have some old (pre digital) 3x5 prints from an old Fujica camera that used 35mm film. The photos look sharp and I scanned them into my computer (canon scanner). When I open the photo with wndows 10 photo viewer I can enlarge the picture (prss the + button to zoom) and the picture remains sharp looking regardless of how big I make it. But if I want to print it larger ill use resize feature in any phot software including photosho elements  and  the larger I make it the more pixalated it gets. So it looks great on the viewer when enlarged but it looks blurry if I actually want to print after I try to resize it. I know Im missing something fundamental here. Any advice is appreicated. thanks

[Peru Bob]

What is the pixel size of the original scan?

What pixel size is the enlarged photo?

[seniornewbie]

Thank you Peru Bob for your very specific question. I have come to the conclusion that I am lacking in knowledge about this subject to have an intelligent conversation. I tried to scan a old 35mm photo and it came out as a small  picture in the upper left hand corner of what appears to be an 8x11 sheet in my computer viewer. I automatically assumed it would print that way. So I tried to resize, resample it bigger. When I first posted the problem to community it appeard that when I resized it the picture became blurry. Now I cannot reproduce the problem as stated. Now when I try to resize the picture it remaims the same look but the pixels get lower and the size (MB) get smaller or they remain the same. I clearly dont know what Im doing. The original pixels after the first scan were 7650x9900, 600dpi and 24 bit depth. Ive tried different progrmas like faststone and elements and tried different scans like tiff, png, bmp and get different amonts of pixels but they all look the same on the viewer- picture in upper left hand corner. So I did some research and read Wayne Fultons writings and another page called Shutha. I now realize this is a subject that is much more complcaited than i thought and I need alot of studying to figure it out. I didnt even know that resizing and resampling were different things, Then throw in cropping and it gets crazier. Very intensive information. I ended up taking my original photo to Walgreens and getting it enlarged pretty cheap. But my work is cut out for me to learn this. Next time Ill try to have more informed and intelligent questions before I consult with the community. Thanks much 

[Glenn 8675309]

Printing,, and what you see on your screen are two different things.   Images on your screen don't need to be high resolution to look good on your screen. 

 Images on your screen (unless you but a super high resolution screen) are only between 95 and 120ppi--- that's all they need to be to look good on your screen.

Printing is measured in DPI. 

Vast majority of images used online (and viewed on your screen) are 72 ppi by default.

You will see 72 ppi and 96ppi ALOT- it's from the original computer displays of  APPLE  and WINDOWS.

In the 1980's, computer screens did have resolutions of 72 PPI, it was because dot matrix printers printed at 144 DPI, so what you saw on the screen was going to be roughly equal to what was printed on a 2 to 1 scale. As screens and printers have improved, the 72 DPI rule for web resolution is now completely irrelevant. Literally no one uses 72 ppi resolution monitors anymore. Monitors these days, especially Apple's retina displays, have much greater resolutions, commonly 227 DPI. Some smartphones even display at up to 500 dpi. So the computer monitor you're currently staring at, unless it was made before yours truly was born, has a resolution that is much higher than 72 DPI.

Microsoft (In it's early days) realized that they wanted their displays (CRT's-- the original computer screens) to match up with the printed stuff in size when viewed on a screen from a standard distance.  You could hold up a ruler to your screen and measure three inches of text, and it would be three inches printed.  In the earliest days of printing you had only two sizes:  (1) Take it (2) Leave it. 

All this PPI stuff is based upon printing value that have been around for a couple of centuries.  In the late nineteenth century, the point system—devised a century earlier by Pierre Fournier—was adopted by the printing industry. The point is used to describe the difference in size among typefaces, leading, and other aspects of composition.

In the printing industry (think newspapers and printed magazines) there are 72 vertical points to an inch.  A 72 point font would print at 1 inch tall.   A 36 point font would print at 1/2 and inch tall.  An 18 point font?  1/4 of an icnh tall- that's where font sizes come from. 

PRINTERS back in the day were dot matrix.  They were vers low resolution.    Heck, I had a printer from radio shack that If I wanted to change font size I had to flip some toggle switches buried in the printer.

The original dot matrix printer, introduced in 1970 had a print head that could print a  character seven dots tall, and 5 dots wide- that was it's resolution.

WHAT YOU ARE EXPERIENCING is the difference between what you seen on your screen (low resolution) compared to what what you print (high resolution).

 A RULE OF THUMB:   Every 300 of  PPI will print at 1 inch at 300 DPI

When I scanned 35 slides a while ago I did it at 1200ppi- I wanted that scalabillity ofthe image- to be printed at a 8 x 10 inch size and look great. 

[seniornewbie]

thanks for your answer and some history. I think I now understand a few things. A computer screen viewer can be much different than a printed product. 300 PPI equals one inch of the picture. With the print it would be 300 DPI per inch. It stands to reason that if one tried to print a picture 8x10 at 300 PPI the amount of pixels would be much higher. I have alot to learn. 

[Glenn 8675309]

I always tell people, do what makes you happy.   I often take images to a local copy place and tell em "Print this as is 11 x 17- and to ignore that 300 dpi message you will get."

For school stuff, like powerpoint slides they still came out looking good.   

[seniornewbie]

🙂