The truth about High Resolution images.

High resolution images included or needed.

The real truth is that there are no hard and fast rules as to what constitutes a high resolution image. So buyer beware….. last month I was handed a USB stick with a set of high rez images on it. The tiny little files on the stick where barely large enough to make even the smallest print. Whereas the person who had the files expected to make substancial wall sized prints from them. After some back and forth between the person who owed the USB Stick and the image supplier, the advice was to get me to “Just Upsize” the files. Therein lies the next problem. People often upsize or uprez and image to be able to make bigger prints. Doing so, doesn’t actually increase the resolution of the image. Upsizing, regardless of how it’s done. Will not increase the real resolution of a file. Yes it increases the file size and interpolates the information in that file to make a considered, guess at what information to add to increase the file size. But the bottom line is… If the data or image resolution isn’t there in the first place, any interpolation will be inaccurate and often aesthetically annoying.

DPI or Dots Per Inch isn’t an indication of resolution.

Well actually it is, but not in the way most people seem to understand it. DPI comes to us from the printing industry and refers to the number of dots of ink to be laid down per inch on paper during the print process. So if you have a picture that is one inch square at 300 DPI there would be 300 dots across and 300 dots of ink down or 300 x 300 which equals 90,000 dots of ink making up the picture. This would be considered a fairly high resolution image. But not a very big image. Think like a thumbnail on an index page. Ringing me and asking for a high resolution image of 300 DPI tells me nothing. Because unless I know the size the image is to be printed the statement 300DPI is worthless in determining the image size you will need.

Think it this way. You walk in to a paint shop and ask for some paint to paint your house. You ask for a tin of Primrose Pink paint. The person behind the counter asksĀ  how much Primrose Pink you need and you reply that you are going to use 3 coats of paint. How much paint do you need? Nobody knows because you have told the assistant you are using 3 coats (think of that as the resolution) but haven’t said how big the house is, or whether you are painting just the inside or the whole house. That’s exactly how it is if you tell me you want a high resolution file without telling me how big the image is going to be used.

So how do you judge the resolution of a photo?

The very short abbreviated answer is by the number of pixels in a file. Measured pixels high x pixels wide. Usually quantified as MP or megapixels. The more pixels you have the higher resolution the image is. So a 6MP camera image will have less resolution than an IQ180 80MP medium format digital camera back. A whole lot less resolution in fact. There are variables of course. There are pixels and then there are pixels, if you know what I mean. Not all pixels are made equal. There are great pixels and then then there are some very ordinary pixels, plus a whole lot in between. So when the camera sales person tells you that brand A is better than brand B because brand A has more megapixels. That is only part of the story. A very small part as it turns out. For example if I have a 22MP camera filled with good high quality pixels, but then take a photo through a lens designed to be used with a 3MP camera. Chances are, I will get a large image file but one that will have only the resolution of a 3MP camera. For a digital sensor to be able to resolve high resolution images. Apart from needing to be made from good quality pixels. The lens in front of the sensor needs to be capable of resolving the scene in front of it at high resolution.

Determining the size of an image file is best done when the file is open. Because different file types have differing compression rations or, like JPEG files, compression amounts can be chosen by the operator. Again highly compressed image files may loose resolution simple because so much of the files image data is tossed away during the compression process.

The tale of 3 pictures

Below are 3 images all from one file, shot on location with a beautiful young lady, Ruby is her name. This image was made while testing lighting and during the makeup session, is totally as shot, no retouching or density, colour or sharpening corrections applied.

image downsized from a high resolution file for web useage.

This first image is the full file straight out of the camera converted from 16bit raw file to a jpeg for web use.

Close up crop of a models eye

The above image is a 100% crop from the original high resolution file. Still no retouching other than converting to a format understood by the internet. Check out the detail in particular the eye lashes.

models eye cropped from a web resolution photo for illustrating low resolution.

Check out the image above. Same file but this time the crop of Ruby’s eye is taken from the first web sized image above. The last two images have roughly the same file size. The drastic difference is between the two is from one being downsized from a high resolution file while the last blurry picture is the same crop from a low resolution image file. Take notice of the really blotchy skin on the left hand side of the photo. This is a result of the imaging software trying to interpolate the image as it tried to upsize the photo.

I know it looks extreme but trust me when I say we have several case of people downloading a proof file such as the one of Ruby full frame above. Specially with our stock image web site where it is cheaper to license and download a small file than a larger file. So naturally people buy the smallest size and then try and uprez it to save a few dollars. The very next thing we hear is that someone isn’t happy with the quality of our stock files, because they print all blurry……. No bloody kidding Einstein!!!

The bottom line.

Anytime people start talking about high resolution proofs/photos/files/images. You need to know that there is no standard written in law. So you need to clarify just what size the high resolution images are or will be. You need to know that upsizing works to a point and then it’s down hill all the way. If image detail isn’t there in the first place then ts never going to magically appear, no matter what some snake oil salesman tells you.

Just as a finishing note. Late last year I was asked by a client, for a high resolution image file for an advertising campaign. We handed him a 240MBĀ  print ready file… way bigger than needed but just to be safe. A few days later I get a phone call from a not to happy printer who as he so beautifully put it. “I’m sick of you dickhead photographers who don’t know what a high resolution image is.” After a bit of mucking around and a couple of phone calls it seems someone in the clients office decided that the file I supplied was to big to email so down sized it to web size. We just assumed the printer would be smart enough to resize it up again when he got it.

I spent some time trying to explain why that wouldn’t work but to no avail. They simply replied that they do it all the time, without problems…… Yeah right!

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