What is the best file size for my print?
Picking the correct file size can be tricky. Understand the basics of pixels and resolution to help you choose the best result for your images.
What does file size mean to you? For many casual photographers, it's simply an indicator of how long it'll take to send an image digitally. However, the size of an image has a huge bearing on the quality you get through professional photo printing.
What are pixels?
To have a complete grasp on file size in photography, it's important to understand exactly what pixels are and what they do.
Pixels are responsible for absorbing light in a camera's imaging sensor for the camera to transform into photographs. They are also the microscopic dots that make up the images we see on digital displays. Each screen is comprised of thousands (sometimes millions) of pixels, usually invisible to the naked eye.
When pixels are visible, an image is pixelated - and it's the wrong result for quality photography.
The blurry blocks you can see in the image are pixels.
What is resolution?
Because each photograph is full of microscopic pixels, we also receive a specific pixel dimension that allows us to know how many exact pixels are in the image. Resolution simply means how closely these pixels are grouped together.
The more technical term is dots per inch (dpi) or pixels per inch (ppi). An industry-standard resolution count is 240 - 300 dpi, however, each photographer has the freedom to choose their preferred resolution.
What do these two factors have to do with file size?
One reason why resolution and pixels are so important when distinguishing file size is that you simply can't expect a high quality result with only one factor in order - they all must be in sync. The number of pixels captured with each shot directly relates to file size.
Take the time to perfect your file size before photo printing.
How do we calculate file size?
For a standard 4 x 6 inch image set at 300 dpi (300 dots/pixels per inch) we can see that the six inch length will contain 6 x 300 = 1800 pixels and for the four inch length, 4 x 300 = 1200. Multiply these for your pixel total - 2.16 million.
With the total number of pixels calculated, the file size can now be determined. Depending on whether the image is greyscale, red, green and blue (RGB) or cyan, magenta, yellow and key/black (CMYK), there will either be 1, 3 or 4 bytes per pixel (8 bits per channel images) or 2, 6 or 8 bytes per pixel.(16 bits per channel image)
This can be worked out by adding up the number of pixels in an image to reach the file size figure. In greyscale images, each pixel is 8 bits in file size and has the same number of bytes as there are pixels. With our 2,160,000 pixels, we know that the file size is the same (2,160,000 bytes or around 2.1 MB).
A standard resolution count chosen by many photographers in the industry is 240 - 300 dpi.
It is important to note that here at Oliphan, we only accept RGB or greyscale mode files and the sRGB (standard red, green, blue) profile must be used. Any other setting won't allow the colours to be printed correctly. We use sRGB as it makes for great colouration, especially on images portraying skin tone. Our latest printers are designed to print this setting to a very high standard so please be sure to check your image is saved to this profile.
After spending the time capturing beautiful shots, don't rush the editing process. Work out the correct file size before sending your images for premium photo printing at Oliphan.
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