Resizing and Printing

[alan]

>I do not think that this is correct. If for ex&le the highest resolution that your scanner can provide is 4,000 ppi., then this will remain so, no matter what size of image you scan. You will not be able to obtain a higher resolution by cropping - potential pixels will be lost in exactly the same way that real pixels would be lost by cropping in Photoshop. You may possibly save some scanning time, but that is all!

Alan

 

[percywalker]

>Paul, I want to thank you and congradulate you on the excellent writing on >resolution and printing. Your piece was the most clear, concise, and yet >appropriately thorough explaination I have yet to read even from the >magazines and books. Well done! - Fred

 

[bobbl46]

Agree with Fred.

Thanks Paul, your post will go down as a classic, and should be quoted/referred to ad infinitum.

Cheers, Bob.

 

[albert4321]

Good discussions.

I have printed my B&W images at the lower printer resolution and got better result (smoother in tone) than the highest printer resolution. It kind of make sense from Pual's write up.

I do have a question, here everyone refers the image resolution at 360ppi. But I have been setting my image to 300ppi (based on the books I read.) Should I use 360ppi in the future and get real benefit from inkject printing?

Al

 

[paul_schliesser]

Should I use 360ppi in the future and get real benefit from inkject printing?

Al,

My assumption is that Epson's printer software will build cells that divide evenly into the number of printer dots per inch - for a 720/1440/2880 printer, reasonable resolutions would be 180, 240, 288, and 360 ppi. 300 divided into 1440 gives you 4.8 - you could have 4x4 dots (360 ppi) or 5x5 dots (288 ppi) per cell, but not 4.8x4.8 dots per cell. Epson may be playing some other games with this; for instance, they may make rectangular cells or print with different vertical and horizontal resolutions under some conditions. But I assume that the printer simply rounds the resolution to the nearest value that fits evenly.

In offset printing, you always want to have more than one pixel per halftone dot (a halftone dot is made by printer dots in a cell, similarly to the way an inkjet breaks down an image). This has an anti-aliasing effect and minimizes digital artifacts like jaggies along sharp diagonal edges. In halftone printing, you can start to see these effects if the file ppi and the number of halftone cells are too close to each other. It's normal for the dpi of the file to be 2 times higher, and never less than 1.5 times higher. Almost everything in publishing is standardized at 300 ppi files sizes, and printing is commonly at 133 or 150 halftone dots per inch.

This seems to be much less of an issue with inkjets, but yes, I'd recommend that you try to have at least as many ppi in your file as your printing resolution. To be honest, I don't know how much of a real-world difference you'll see, but I'd bet you could see cleaner edges in photos with lots of geometric shapes and straight lines, but it might be a subtle difference.

I have an Epson 1280 with a continuous inking system, but I have not been using it for fine-art printing. I use it mostly for producing graphic design layouts and things like that. I have not experimented with getting the maximum photo quality out of it, so I'm speaking here more from theory than from practical experience or experimentation, so your mileage may vary.

- Paul