Not sure what’s meant by image resolution? We explain what it is, why it matters and what to do to make sure your images end up in the best possible quality.

What is image resolution?

In photography, the term resolution can mean different things. When we talk about image resolution, however, what we are usually referring to is the pixel resolution – that is, the number of pixels in the image. 

The digital images that originate from our cameras and smartphones are made up of pixels, so knowing how many pixels are present gives us an idea of what kind of image we’re dealing with.

 

How is image resolution stated?

Image resolution is typically expressed as a horizontal x vertical measurement. So, an image resolution of 6000 x 4000 tells us that the image measures 6000 pixels in width and 4000 pixels in height. Multiplying the two figures together gives us the second way this is commonly stated, namely as megapixels. 6000 x 4000 equals 24,000,000, which is more commonly written as 24 megapixels (MP).

 

How can I find out the resolution of my images?

Your camera’s sensor will naturally capture and output images at a certain resolution. If your camera has a 24MP sensor, it will output images at around this level, though many modern cameras tend to have sensors with an even higher pixel count.

It should be possible to check the number of pixels in the metadata of the image, which is the information that’s attached to each image. You can view this in your camera once your images have been captured, or in a software program such as Photoshop. If you’re using a Mac, you can also just right-click on the file of the image and select Get Info, while PC users can right-click on the file and select Properties, before viewing the resolution in the Details tab

If you’ve already uploaded your images to SmartFrame, you can view their resolution at any time by simply clicking on the image in question and checking the figure next to Image size.

 

Do more pixels mean more detail?

Every pixel in an image can only take on a single value. In other words, it’s not possible to have more than one detail within a pixel. So, the higher the number of pixels, the greater the potential for more detail in the image. 

‘Potential’ is the operative word here; the level of detail in images depends on more than simply the number of pixels present. Image noise, lens quality and photographic technique all have a significant hand in how detailed an image ends up, as does the specific processing applied to the image upon its capture, and the strength – or absence – of anti-aliasing filters in front of the sensor. A higher resolution image may give you a bigger image to view, but this doesn’t necessarily mean it will display more detail.

Is resolution the same as sharpness?

Not quite, no. Sharpness concerns how clearly defined details within images appear, and is, strictly speaking, subjective (whereas the number of pixels in an image can be easily quantified). It’s entirely possible to have an image that’s high in resolution that doesn’t quite look sharp, just as it’s possible to have a low-resolution image that appears nice and crisp. Much depends on how the image is being viewed, from what distance, and exactly who is viewing it.

So what happens when you sharpen images using software? Typically the contrast at the edges between different details will increase, which gives the impression of crisper detail. But you aren’t actually adding any extra information to the image when you do this.

 

Should I post low-resolution or high-resolution files online?

The way an image can be used is limited to some degree by the number of pixels it contains. Photographers looking to protect their work often upload low-resolution versions of their images in an effort to discourage theft. This makes a lot of sense, although it does lessen the impact such an image has as it can only be viewed up to a particular size. 

There are, however, ways in which you can continue to share images at a higher resolution while keeping them protected. One option is to watermark your images, which also discourages theft, although photographers will typically apply these to low-resolution images to be extra cautious. SmartFrame’s approach combines download and screenshot protection with dynamic watermarking for maximum security, which allows for high-resolution images to be shared and displayed securely.

 

What is an example of a low-resolution image?

There is no specific cut-off point for a low-resolution image as it really depends on how and where it is being used. But an image with a three-figure pixel count in both dimensions would rarely be considered high-resolution for most uses. 

Even an image that measures 1920 x 1080 pixels, for example, would only equate to around 2MP. This is usually fine for online use but far smaller than what today’s cameras and phones produce as standard. 

 

What is an example of a high-resolution image?

Again, there are no defined boundaries here, but an image straight from a modern camera captured on its highest-quality settings would typically be deemed to be high enough in resolution for most purposes.

Current cameras tend to output images at around 24MP, 36MP and 45MP (and beyond), and these contain information well in excess of modern computer and television displays. Some cameras even have high-resolution modes that quickly capture a number of images of the same subject and combine them into a single file, which ends up with an image resolution equivalent to around 180MP or 200MP.

What resolution do I need for my images?

What is it you’re photographing? How is it being displayed? Who is viewing it and from what distance? These are the sorts of things you need to first ask yourself if you’re to answer the above question.

If an image is destined for a modern computer display, it doesn’t need to be very high in resolution at all. The screen on a current-generation 16-inch Macbook Pro, for example, has a resolution of around 5.9MP, so images straight from today’s cameras or phones would easily satisfy this. It’s also worth remembering that, usually, we’re not using the whole display to view an image anyway.

If you plan on using Hyper Zoom, or severely cropping your images, then starting with an image in the highest resolution makes the most sense. It’s a good idea to always capture images in the highest quality to begin with – and ideally, to capture Raw files too – so that you have maximum flexibility later on.

 

What are the pros and cons of low-resolution images?

Low-resolution images will not be able to show the same level of detail as higher resolution ones, but what they may lack in detail they make up for in efficiency. 

These are usually smaller in terms of their file size than high-resolution images, which means they can be uploaded more easily online, or sent in emails and through messaging services like WhatsApp and Facebook Messenger.

Note: the exact size of the file depends in large part on the contents of the image and the level of compression applied (if any). It’s possible to make high-resolution files small in file size by using compression, which JPEGs use as standard.

 

I’ve heard the terms dpi and ppi? What do these mean?

Ppi stands for pixels per inch, and this is a measure of the density of pixels within an image. It may also be used to refer to a display used to show images; the aforementioned Macbook Pro, for example, which has a Retina display, has 226 pixels per inch, while more junior Macbooks have far less.

Dpi, which stands for dots per inch, is similar in principle, but it relates to printing, where there are dots instead of pixels that make up the image. Traditionally, photographers have aimed to print their images at a level of 300dpi for good clarity, but it’s possible to print at a lower dpi – and so, a larger size – and still achieve more than acceptable results. This is particularly true when an image is hung on a wall, where it will typically be viewed from a greater distance than when a print is held.

 

What is the relationship between 4K and resolution?

4K is a term that’s been used widely in recent years, be it on new televisions and computer displays through to the likes of Netflix and other content providers. Typically, the term is used to describe either a video or piece of content that can be recorded, played or streamed at around 4000 pixels in width, or a device that’s capable of displaying it at this level.

While some manufacturers have used the term to refer to images, the past few generations of modern cameras have been capable of producing images well in excess of 4000 pixels across, so the term is not used as widely here as it is for videos.

It’s only been in the last few years that 4K video has been widely available on consumer-level DSLRs and mirrorless cameras, with cameras before this recording at a maximum Full HD (1920 x 1080 pixels).

For videos and displays, the term typically refers to one of two specifications: DCI 4K (4096 × 2160 pixels) and UHD 4K (3840 × 2160 pixels). Most cameras that are capable of recording 4K footage, and displays that are said to be 4K ready, work to the 4K UHD standard, though more cameras today are adopting both.

 

How do I increase the resolution of my images?

Once an image has been captured at a particular resolution, it’s not possible to increase its resolution without affecting its quality. While it’s completely possible to add pixels by increasing the dimensions of the image in software, this is essentially a process of guesswork using existing pixels, rather than something that can retroactively add details that weren’t there to begin with.

So, once again, the best thing to do is to make sure you’re capturing images at the highest-quality settings available on your camera. It should be clear which option this is: it will typically be marked ‘Large’, or with the specific megapixel count that corresponds to the sensor inside it. 

If you have a modern camera it may also have the aforementioned high-resolution mode, although this will typically only be practical when using a tripod, and with a static subject too. Even so, it will give you an image that is significantly higher in its pixel count than usual, so it’s worth considering.

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