Image Resolution and photo restoration. Part 1/2
Before we start restoring any photographs we really need to understand printing resolution so we know how big our final photo restoration can be printed
The amount of times I have received requests for information on the ins and outs of printing resolution. I have read many an articles and to be frank none of the put it very simply. Here is my version.
You own a printer and you own a digital camera or have some digital images you wish to print. Just how big can you print and it still look good? Well it amounts to several factors but the best one is whatever looks good to you. This sounds very amateurish and am sure some of you might wince at my short answer, but really if you are happy with the result then that’s an important factor. But if you are not happy then maybe you are viewing it too close, viewing distance is also another factor. Seriously do you look at an A3 picture from 10 inches away or do you stand back and admire the picture for what it is? You should view it from a distance that is right for the size of image. If you are too close then you may see the digital artefacts or pixels that the image is made up from, this is most likely to happen on larger photos than 10×8 inches or on posters.
Ink Jet printers often have an enormous printing resolution, for example 4800x 2400 dpi, dots per inch. You can immediately get confused if you try and equate this with the resolution of your image, for example your cameras resolution is 2816 x 2120 or 6 million pixels. If you print the image using the printers maximum resolution, then surely your image will appear less than an inch big? Yes, but this is not how you should interpret it, you cannot literally equate the two devices in this way, I will explain
Commercial printers who uses printing presses used to publish books or glossy magazines always request images at 300dpi as that is the industry standard. This is a good optimum printing resolution for us too, and this can be used as a base for our printing equation. Simply put, what ever your image is in size it can be printed at 300 dpi. Well actually its ppi or pixels per inch, as you camera or image is digital and in pixels, not dots like a printer. For example even a 640 x 480 resolution image can be 300 dpi but will only measure just over 2 x 1 inches achieved by simply dividing the dots per inch into the pixel size of the image. When we get larger images such as 2816 x 2120 we can see that at the optimum printing resolution of 300 dpi. We spread those pixels over 300 pixels per inch and get a image size on paper of 9.4 x 7 inches.
Providing a Quality photo restoration service and repair
The higher the resolution of your scan the more image you have to restore. By this I mean the more texture and grain and tone you can borrow to mend and refer to, to patch up any creases or restore missing parts, or perhaps even rebuild completely new ones. Storage is also so cheap these days it doesn’t hurt to give it the full treatment.
I’ve been scanning old photos at 600dpi as some of them are very small, my father has asked for enlargements, and I thought it’s probably safer to scan heavy rather than run the risk of spending a lot of time working on a file only to find later that I should have made it bigger. For enlargements of, for example small single figures in group photos surely higher is better?
I wonder however whether 600dpi is overkill. I’ve seen acceptable printouts of illustrations at 150dpi, clients rarely require higher than 350dpi for publishing (except for B/W line drawings which need to be scanned in bitmap at 1200dpi).
Perhaps with photo restoration I’m just nervous that I’m responsible for a family legacy, so don’t want to sell my descendants short.