Taking photographs while on the road is a great way to hold on to visual proof of a great vacation or an interesting off-road adventure. Photos also help you capture the colors, life, and atmosphere of your subject. Having the right camera is important. Thankfully, today’s smartphone cameras are a good alternative for taking both social-media friendly photos but also high-resolution images for printing. Eight to twelve megapixels are more than enough for capturing photographs that are the optimum resolution for print and digital publications.
To determine if your photo is good enough for printing, it’s important to first understand how thousands of tiny little squares can make or break image quality.
Understanding Pixels
What is a pixel? In short, a pixel is the smallest unit of information that makes up a picture—the more the better. It’s a basic unit of programmable color on a computer display or in an image. Ever zoomed in close to a photo to find tiny squares of colors? Those are pixels. If you can see those squares at 100% (normal size), then the image is said to be “pixelated.”
Remember when people used to scan personal pictures and use them as a windows background? Windows would take that 640×480 wide photo and stretch it to fill up an 800×600 screen. The image usually looked fuzzy as the same number of pixels (the 640×480) were stretched to fill up the full 800×600 space. What may look like a great shot of Niagara Falls may turn out to be a fuzzy mess of colored dots when you see it on screen.
Resolution refers to the number of pixels in an image. Have you ever tried to upload a picture to the Web and it says something like, “picture must be 1200×600”? This means that there are 1200 pixels from one side to the other (width) and 600 pixels from top to bottom (height).
The term dpi stands for dots per inch and ppi stands for pixels per inch. The terms are often used interchangeably as the word dot essentially means pixels. When you download your images, they will be extracted at the default size with a default resolution of 72 pixels, or squares of color, per inch. Some fancier cameras import at 150 dpi, which is still web friendly but not necessarily print friendly. High-resolution images have at least 300 pixels per inch (or 300 dpi), which makes them good for printing. Remember how I said earlier that the more pixels the better? This is where we get into megapixels.
Megapixels
Megapixels (Mp) determine the resolution of a digital photo. One megapixel equals one million pixels in an image. In simplest terms, it is the horizontal pixel of a photo multiplied by its vertical dimension. Like with pixels, the higher the megapixel the better. Knowing your camera’s megapixel size will help you determine what your actual size is. Here are a few examples. The exact dimensions will vary depending on the camera manufacturer, but not by much.
- The default resolution on a camera with 8 megapixels, like the iPhone 6, is 3456×2304. That is 3456 pixels wide and 2304 pixels high (48×32 inches) in size at its highest resolution or “Actual Size.”
- 3456 times 2304 = 7,962,624 pixels or 7.96 megapixels. (Hey!)
- Maximum print size is 11.52 in. by 7.68 in. at 300 dpi
- The default resolution on a camera with 12 megapixels, like the Samsung Galaxy S8, is 4032 pixels wide and 3024 pixels high (56×42 inches) at the highest resolution or “Actual Size.”
- 4032 times 3024 = 12,192,768 pixels or 12 megapixels.
- Maximum print size is 13.44 in. by 10.08 in. at 300 dpi
The key to maintaining such high numbers is to export it as “Actual Size” directly from your cell phone. You can email a high-resolution photo to yourself, just be sure to select the largest size. A better option is to download directly from your computer by either sharing to cloud programs like Dropbox or Google Images or using an adapter. Don’t send the image as a text as more likely than not? It will be resized and compressed.
What about dpi?
The term dpi stands for dots per inch and ppi stands for pixels per inch. The terms are often used interchangeably as the word dot essentially means pixels. When you download your images, they will be extracted at the default size with a default resolution of 72 pixels, or squares of color, per inch.
Some fancier cameras import at 150 dpi, which is still web friendly but not necessarily print friendly. High-resolution images must have at least 300 pixels per inch (or 300 dpi).
For print publications, 300 dpi/PPI is the minimum size that must be used. Whether you send it to a designer or do it yourself, the image has to be converted from 72 dpi to 300 dpi. Otherwise when the image prints, it will be pixelated. This is where it gets a little tricky.
For online or digital publishing, the ideal is 72 dpi. A 92 or 150 dpi has become more common as web speeds increase, but 72 dpi is still preferred. As a good rule of thumb, your file size should be between 20 and 200 kilobytes (KB).
Here’s a simple formula to help you determine your needed resolution.
Pixels / DPI = Inches
Let’s take that it 4032 pixels wide and 3024 pixels tall image with a default resolution of 72 dpi.
- 4032/72 = 56 and 3024/72=42.25 in. So for a digital image, it would be 56 inches wide and 42.25 inches tall.
We need to convert that number for a high-resolution version to print. The minimum dpi is 300.
- 4032/300 = 13.44 and 3024/300 = 10.08 in. So, the printed, high-res version would be 13.44 inches wide and 10.08 inches tall.
The good news is that if a graphic artist imports the image into Adobe InDesign for a print layout, the image is large enough to cover an entire page, width-wise.
How to Change Resolution in Photoshop
Step 1. Select the command Image on the toolbar and down to Image Size.
Step 2. Uncheck the “Resample” Image button if you want to keep the total amount of pixels. This changes the width and height (in inches) but leaves the pixels the same. Turn off the resampling because resampling can result in poorer image quality. Leaving it on and changing your resolution can either delete pixels (if you make it smaller) or add pixels (if you make it bigger). It destroys your original pixel set. Just uncheck it for the best quality.
Step 3. Change the Resolution to 300 Pixels/Inch
Step 4. Press the OK button.
Notice that it goes down from 56 inches down to 13.44 inches at 300 dpi. For an 8.5 x 11-inch book, this would work great as a photo that goes across the 8.5-inch page with room enough to “bleed” off the page. Also, note that the pixels themselves didn’t change. If we pull down the Inches tab and look at the pixels, they are still at 4023×3024 as the number of pixels on the screen didn’t change. We simply changed the dpi for the dots per inch, which is a printer term. If you’re wanting to use the image in a printed publication (book, report, etc.), then you want to ensure that the size of the image at 300 dpi in inches is enough to fit on your page.
The image is not large enough, however, for a book cover. If the image was a vertical picture to start with at 3024×4032 (42×56 inches), then with a width of 10 inches and a height of 13 inches, you would have enough room to provide a great cover with room for maneuver. Don’t try cropping the edges to make the picture vertical and then resizing it. This will quickly destroy the integrity of the photo and increase pixelation.
In short, a photo taken with a camera above 8 megapixels will be sufficient as long as proper lighting and framing are used, and that zooming isn’t out of control.
How to Determine your Image Dimensions
Don’t have access to a photo editing program like Adobe Photoshop but want to determine what size your image would be?
Here’s a tip for finding out your image’s dimensions on a Windows PC.
- After you’ve downloaded your image, right-click on it and hit Properties.
- Hit the “Details” tab.
- Under “Image” you’ll find the dimensions. In this example, the image is 3024×4032.
On a Mac, Control+click on an image to see the image’s properties.
- Click Finder on your Dock.
- Find the image you want to see.
- Control+click (ctrl+click) on your image.
- In the menu, click Get Info. Expand the More Info: section to see your image’s dimensions.
After you have determined the dimensions (3024×4032), use the pixels/dpi = inches formula or go online to an online calculator like this one at Auction Repair or UpRoer.
Note: Enlarging digital photos, or upsizing, is never recommended. You’ll wind up with a pixelated image. If you want to have a picture that spreads across two columns in a magazine, ensure that the width is a minimum of 7.5 inches wide at 300 dpi. Don’t take the same photo into a photo editing software and try to enlarge it.
Optical vs Digital Zoom
In photography, we use the term zoom to indicate making the subject of a photo appear closer than its actual distance. Cameras use two different type of zoom
Optical zoom uses an arrangement of lenses to manipulate the light entering the camera—point and shoot cameras, mirrorless, and DSLR cameras use this feature.
Smartphones, however, are often limited to what is called digital zoom. Digital zoom takes a photo of an image first and then digitally zooms in on the subject to fill the frame. It essentially crops an image to make the subject appear closer and is not a true close-up. The quality suffers, and the picture is noticeably grainy or pixelated. If you must take pictures from a distance, a point-and-shoot camera or DSLR might be a better option. I highly recommend the Canon PowerShot SX730 digital camera with its 21 megapixels and 40x optical zoom.
Tips for Improving Photos Taken on a Smartphone
If you’re on the job and don’t have the time or inclination to carry around a large camera, your smartphone (or even tablet) is often more than enough to get a great photo. These photos can also be used for your online training and for printing in a magazine article or book.
- The quickest tip to improving the digital zoom on your smartphone is to try and not go above 2x digital zoom. Anything at 4x or above will make your photo look like a painting and destroy the image quality.
- Try to use a tripod. The more you to zoom in the more unsteady the shot will become.
- Purchase an “add-on” camera, like the Insta360 for iPhones. It gives you the features of the more expensive point-and-shoot and DSLR. It attaches right on to your smartphone, so it’s less bulk to carry around. Other options include the ION360 U – 4K Ultra HD for Android users.
- You can also purchase lenses, such as the Photojojo iPhone and Android lenses or the Olloclip iPhone 4-in-1 lens. Find a set of lens to match your particular smartphone on Amazon.com.
- Try to get as much lighting, especially natural lighting (sunlight) as possible. The hour after sunrise and after sunset is considered the best light for photos, but that may be an impossible time if you’re on the job. You can also get LED units like LED Flash Fill Light for Smartphones.
- Download apps like Camera+ or ProCam 2 on iPhones and Camera FV-5 for Android. Why? The aperture is often the most important feature. The aperture is the opening in the lens and is measured in f-stops. A small f-stop like f/1.8 is a wide opening and the larger the aperture, the narrow the lens. The wider the aperture, the more light goes into the camera and you get a brighter photo. Most smartphones and point-and-shoot compact cameras, however, have a decent enough aperture so if you are not a photography buff, it doesn’t matter. Apps such as Manual or Camera+ allow you to select the aperture, ISO for use on your smartphone.
Do you have any tips for producing high-quality photos using a smartphone?
Parts of this post were cross-posted on Publimetry.com.
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