1 pixel by 1 pixel image at 72ppi

Wrong! Professional printers (as compared to your home printer) need images that are at 300 dpi to print. Fine point here – last paragraph I wrote ppi, this paragraph is about dpi. The difference is, ppi is based on pixels on a screen. Screen resolution varies from your cell phone to a huge projection TV screen. The pixels on a projection screen are much larger than those on your phone or computer. Dpi is based on ink drops, which are pretty much all the same size relatively speaking. We’re not talking Jackson Pollock, we’re talking about ink on a press. When you look at a printed piece under a good magnifying glass, you will see the little dots. It takes about 4 times as many dots per inch to print an image as it does pixels per inch to view it on screen.

Here’s what you see on a black and white image, the dot pattern of the dog photo is the printed black ink dots.

So finally, this is the difference between high resolution and low. That 11 x 17 image at 72 ppi translates to 2.64 x 4.08 inches at 300 dpi. 300 dpi is a typical resolution that a printer needs. So when your printer says your image that you think looks good on your computer is too small to print, you now understand that he need an image 4 times larger than what you are looking at on screen to print it at the same quality.

Next lesson, RGB vs CMYK.

I shoot with a Nikon camera, which generates raw files with the designation .nef. These files can only be opened with the Nikon program or with Adobe Camera Raw, not Photoshop. I never send out these raw files, as they are exactly that, raw! They have little or no post-processing done. In many cases, this is fine, but for studio or architectural work, my job doesn’t stop there. Please read more about post processing in this article on my website.

a photo being opened in Adobe Camera Raw

Ok, so that’s a raw file. What’s a tif file? Tif stands for tagged image format – yeah, so what. It is generally an uncompressed file, which means it can be very large. It can have layers, with text, masks, paths, special effects, and adjustment layers. But it is a format that is used by graphic designers in creating ads, or in magazine layouts. It is not a file that web browsers understand.

layers palette in Photoshop

Jpgs – now we’re talking! Jpgs have come a long way, they used to be more limited in what they could do and where they could be used. Now, some of the graphic design programs can use jpg files for printing. But for some of us oldtimers, who have limited brain cells left, sometimes it’s just easier to use one file type for one use, and another file type for another. So while I can save the files for printing as a jpg, I’d rather use a tif file. This not only clues me in immediately that it’s a larger file, but it’s also a better image. Every time you save an image as a jpeg, you compress the file. When the file is compressed, you’re telling the computer to just eliminate some pixel information. While one save at the highest quality won’t do much damage, repeated saving of the file, especially at the lower quality settings, can cause the pixelized look, where a blue sky looks blocky and not smooth, or a product will have ragged edges.

jpgs can cause blurry edges

The positive side of jpgs is that it works great for web sites, emailing and printing on your home printer. So when you need an image and your photographer (hopefully me) asks you what format you need, you now have a better idea of what they are talking about.

Next time – hi resolution or low.

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