The interpolation method is how Photoshop chooses the color values of new pixels. Resampling of any kind, especially upsampling, can result in poorer image quality. Removing data is preferable to adding it, since Photoshop will have to guess at how any newly added pixels should look.Ĭhoosing the best interpolation method when upsampling. When you increase the number of pixels in an image without adjusting the dimensions, you are adding more pixels into the same amount of space and increasing the resolution (or amount of detail) held within each inch. Increasing the number of pixels is called upsampling, which adds data to the image. Decreasing the number of pixels is called downsampling, which removes data from your image. The more pixels an image starts with, the higher the resolution. Resolution is measured in pixels-per-inch or PPI. Resampling images in Photoshop means changing their resolutions by adding or subtracting pixels. How resampling and interpolation affect resolution. However, there are some measures you can take in Adobe Photoshop to help you increase resolution while upholding visual quality. You can increase the resolution of a digital image file, but you will lose image quality by doing so. The only way to resize a smaller photo into a larger, high-resolution image without highlighting poor image quality is to take a new photograph or re-scan your image at a higher resolution. Does this work? Not the way Hollywood does it. It’s a familiar scene: a detective asks someone to “enhance” a blurry image on a computer until it becomes clear enough to make out a key piece of evidence. Their printer outputs at 250 PPI (but can handle 100 PPI images), though other services may differ, so always check before preparing your images.Can you enhance the quality of a low-resolution image? Your printer manual or printing service should be able to tell you this.īelow is a screenshot from the website, showing their optimal and minimum image sizes for standard print sizes. Therefore, when cropping and sizing an image for printing, you’ll need to know what PPI the image should be. The result is 2,400 x 3,000 pixels, which is the image resolution you need to print an 8 x 10 image at 300 PPI. Multiply the printed image’s width and height in inches by 300 pixels. To print an 8 x 10 inch image at 300 PPI, use the same math: In other words, it needs to be at least 1200 x 1800 pixels in size. So for example, if you want to print a 4 x 6 inch image at 300 PPI, then you need a file that has at least 4 x 300 (1200) pixels along its short side and 6 x 300 (1800) pixels on the long side. Typical printing PPI values range from 150 to 300 PPI, although some high-end magazines may require images that are 1200 PPI. Most printing services, and indeed your own printer, will require a certain density of pixels in the image (PPI) to be able to render a print that looks good (i.e., with smooth color transitions so you can’t see each individual pixel). This literally refers to the number of pixels in an inch-long line of an image. When you’re printing an image, you may encounter the term PPI or pixels per inch. You can see these pixels if you open a photo and zoom in until you see single blocks of color (as shown below). A pixel can only be one color, and a photograph is made up of a grid of thousands of pixels, each of the different colors that together make up your image. Now, a pixel itself is a single picture element – and for our purposes, it’s the smallest element that your photo can be divided up into. The image above shows the resulting information dialog box. In Photoshop, you can open your image, then choose File > File Info > Camera Data. You can check the width and height of an image using your photo editing software. You and I might call this 14.5 MP, but camera manufacturers round this up and call it a 14.6 MP camera. So by multiplying the number of pixels along the image width by those along the image height, we get the actual number of pixels in the image (4672 x 3104 = 14,501,888). So the ratio comparing the number of pixels along the long edge of the image to the short edge of the image is 3:2.Įach of my full-sized RAW images is 4672 x 3104 pixels in dimension. My camera, like most DSLRs, captures images with an aspect ratio of 1.5. This information tells you nothing about the actual pixel dimensions of the image – it only tells you the total number of pixels that make up the image. So my camera, for example, captures 14.6-megapixel images, which is around 14,600,000 pixels per image (14.6 x 1,000,000). Technically, a megapixel is equal to 1,048,576 pixels in reality, camera manufacturers round this number to 1,000,000 when stating how large of an image the camera will capture.
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