Making Not Taking Photographs

Backstage views on making photographs professionally

Size IS important!

How big should a digital photo file be?

There is so much confusion on this topic I am posting this in a final act of educational desperation.

The fundamental question here is How big does a file need to be to properly reproduce?
There are multiple answers and it all depends on how you are going to use the photo.

Hi, Medium or low resolution is all relative…
The combination of dimensions in inches or centimeters or feet AND pixels per inch determines density of resolution.
I am repeating the above:
The combination of dimensions in inches AND pixels per inch determines density of resolution.

You cannot leave out the word AND. We really, really, really need BOTH sets of numbers.

NOTE: All my numbers here refer to the file when it is OPEN in Photoshop or other pixel editing program… This does not include most of the picture viewing programs that are part of operating systems. When files like jpegs are closed they are compressed…. those numbers are of no consequence to this part of the topic.

For PRINTING PRESS WORK most everyone wants 300 pixels per inch density…

So, to get a good quality image on a printed page 10 inches high you will need a file that is 300ppi at 10 inches (3000 pixels) .
If the file is smaller… say 300ppi at only 5 inches the equivalent size will be 150ppi at 10 inches if you still want to make the image 10 inches tall.
Of course the quality will suffer. Less pixels mean less resolution… less information, less quality.
Really high end presses with up to 12 colors of ink may want images with 36 bit color, 600ppi, and other items… If you are working with those folks you already know everything here… skip on to something else.

Most good ink jet printers want 360ppi at the dimensions you want to print at…
For example  a photo or photo/type combination piece covering 81/2 x 11 paper will need to be 3960 by 3060 pixels to get best quality.
Most of the time 300ppi will do the job just fine though… So, that reduces the file size requirement to 3300 pixels to cover the 11 inches.
Some laser printers work best at 600ppi.

This has nothing to do with the numbers of spray droplets the printer says it puts down… which are in the thousands… this topic is file resolution, not ink droplet resolution…. night and day.

My computer screen (flat panel) shows photos at 90ppi. Older CRT’s were 72 or 80ppi depending upon quality and settings.
This means 900 pixel photo will be shown at 10 inches across in a browser at 100% of it’s size (thus displaying at 90ppi). A 2000 or 3000 or more pixel image will have to be reduced to fit on a screen…

Really high end machines will want 400ppi. Most machines will want 200ppi. Really big images for trade show booth and bill board use can drop to 75 or 100ppi. It all depends upon viewing distance.

TIF and PSD files are preferred for high quality, maximum color depth, and ability to retain layers of images in a single file.
JPEG images are OK if they are created in the final act to produce a file to print from or load onto a website.
JPEG images are not good if you are not finished working on the image and you are going to continue to open and close the file re-saving it as changes are made…. because… JPEGS are compressed with a method of algorithm which throws away information as the files is saved and closed and reassembles it when the file is opened again. Each time you open and close a JPEG (changing it or re-saving it) the image gets worse… further and further compressed. Opening and closing a web page with  jpeg on it has no effect on the picture since you are not “re-saving” the file. E mailing a jpeg from one person to the next to the next WILL eat away at picture quality.

If you are a photographer and you give a rat’s pooper about quality… you will never make photographs in JPEG mode. You shoot in RAW and properly process the photo into a PSD,TIF,  or final cut JPEGs. If you are sending your RAW files to a prepress designer be prepared for total chaos about how they might look when you get the job back… Don’t do this to a designer… They weren’t the photographer(s). They can only guess at how you envisioned the photo. This means you have to ask for dimensions so you can size and ICC profile the photos to meet or exceed the designer’s needs. Now… you go back to the top of this post and start over.

Never use GIF for photographs. There are not enough colors and the image will look like crayon drawings.

BMP is kind of like a jpeg… It’s just Microsoft’s way of giving the finger to the rest of the standardized world to which it does not belong. Anyway, they are weak files… limited bit depth, color and resolution.


I will look into any topic and post an answer.

2 Responses to “Size IS important!”

  1. Chris McDonough said

    I like the intelligence behind your writing. My question: I shoot for a magazine that likes the option of printing two page spreads which amounts to: 11″ x 17″. I’ve shot photos for this double spread w/ a 10 and 12 megapixel cam successfully. Now they’re saying I need a 15 megapixel cam to do these same double spreads. What do I really need to print a 11″ x 17″ double spread?

  2. Mike said

    Not all 12 megapixel cameras are equal… A full frame Canon 5D makes a better picture than a 12 megapixel camera with a smaller sensor… or a CCD sensor. And a 21/4 sized sensor of 20 megapixels will blow away the 21 megapixel sensor of the canon, nikon, or sony.

    I would think a Canon 5D or one of the full frame Nikons would be fine. A 40D or 50D canon or nikon of similar sensor size is right on the edge of real resolution capability for 11x 17 at 300 ppi with a little wiggle room for cropping.

    It also depends upon your skills at RAW processing (jpeg capture is out of the question). If you have a MAC, “RAW DEVELOPER” ($99) is a far superior RAW processor than Lightroom or Photoshop. Actually the Canon software isn’t bad either except it’s slow and clumsy. Over sharpening is the issue…

    Also are your lenses up to par? This is the type of work that shows poor lenses to be real trouble when edge sharpness falls off and the editor freaks out. You need pro leve llenses with apertures that do not change as you zoom and f2.8 or faster so you don;t have to jack up the ISO so high.

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