Glossary and explanations for Digital Negatives

Starting out with making digital negatives you may come across some terms you’ve never seen before, like "gamut", "ppi" and "random dots". This glossary may make a little more sense of it all. If there are more terms you’re unsure about, send an email and we’ll add those words too.

Bleed / bleeding

When there is too much ink on a paper, or the paper does not absorb the ink from an inkjet properly, the colours run into eachother making the image blurry. This is called bleed.

Contact printing

Contact printing is when your image is produced by placing the negative directly onto the photographic material when exposing it to light, thus making an image.

For example, you’ve run out a digital negative on a transparency. You place this on top of a coated cyanotype paper, then expose it to UV light. The final image will be the same size as the negative is.

I.e. you don’t use and enlarger, like you would when printing from 35mm negatives.

Continous tone

The shades of an image is made up of greys ranging from pure black to pure white. Continous tone means that you cannot detect any discontinues between the different shades. A photograph, painting or drawing are natual continous tone images.

Density

The density of a negative means how opaque or transparant it is. The darker the negative is the higher the density is.

Digitize

When you convert an image from a photograph into pixels by for example scanning it, you digitize the image.

DPI

Dots per inch. DPI is a measure of your inkjets resolution. That is now many dots your printer can write for every square inch of paper. Or, rather how many drops of ink it will spray the paper with.

Gimp

Free software used for manipulating images. Website.

Greyscale

A greyscale or grayscale (depending on which continent you’re on) image is made up of different percentage of blacks, from 0% or white, to 100% or pure black. You can also say it’s the tonal scale of grey.

Halftone

A halftone image is made up of a series of dots arranged in lines to simulate a continous tone image. To print a continous tone image it has to be broken down into a series of dots. These dots are calles a halftone screen.

Inkjet printer & resolution

An inkjet printer is used for spraying dots of ink on a piece of paper or transparency, so that you can see the image. How well it does this is dependent on the brand of the printer and also its resolution. All inkjet printers have a resolution measured indpi. A higher resolution, or higher dpi means the printer can render an image with more details. The technique of an inkjet printer is more irregular than that of a laser writer which uses lines. Inkjets uses stochastic screening (stochastic = random). The advantage of this is that details and tones are rendered more natural. The disadvantage is that the maths the printer uses is more complicated and the images take longer to print.

Inverting an image

When you invert an image you turn the blacks into white and the whites into black. In photoshop you can do this easily by just clicking on Image –> Adjustments –> Invert.

Kilobyte or KB

Measure of the size of a digital file. Approximately a thousand bytes, or exactly 1024 bytes.

Laser writer

A laser printer will render your image in different shades of grey (unless you have a colour laser printer). The image is divided into squares. Each square is analyzed how dark or light it is. The square is then divided into lines per inch or lpi. If a square has a 50% shade of grey, 50% of the lines in that square will be filled with black, the rest will be left white. A shade of grey is thus created by 50% of the lines NOT filled with black.

LPI

Lines per inch. LPI is a measure of the resolution of your laserprinter. And how the printer divides the picture into a mesh. Each square of the mesh is then given a percentage of black toner, a greyscale. A common office laser printer typically writes around 100-120 lpi.

Megabyte or MB

1024 kilobytes.

Moirè pattern

Moirè is an ugly circluar pattern that appears sometimes when you scan an already printed image. It is a result of the dots set at the same angle. Try scanning the print slightly tilted. If this doesn’t work, add a 0,5 pt gaussian blur to the scanned image in photoshop.

Photoshop

Software made by Adobe and used for manipulating images.

Pixel

A short of Picture Element and refers to a small square of an image, the smallest unit of an image. The square is filled with a colour. Thousands of these small squares sitting next to eachother make up your digital image.

PPI

Pixels per inch. PPI is used to descripe the resolution of a digital image. It is also a measture of the quality of a scanner. The higher ppi a scanner has, the more detailed the image you scan will be. Sometimes a scanners resolution is wrongly called dpi.

Registration

When you position a film or a plate accurately on top of another.

Resolution

The resolution of an image is the quality of a digital image. Not the artistic quality of course, but how much detail is displayed. There are three definitions of resolution used and mixed up frequently. They are ppi (pixels per inch), dpi (dots per inch) and lpi (lines per inch).

The resolution is the number of pixels, lines or dots used to fill an inch of monitor, paper or film. 300 dpi means your inkjet will use 300 drops of colour per inch of paper. 96 ppi means your monitor will display 96 pixels per inch of montior, and 300 lpi means your laser writer will use 300 lines per inch when writing your image.

Scanning

Scanning is a way of getting a photograph, a printed image or a collage into the computer for turning into a Digital Negative. There are many different types of scanners, desktop scanners, flatbed scanners, drumscanners and filmscanners.

The resolution of a scanner is measured in ppi.When an image is scanned the scanner divided it into lots of small squares, or pixels. The scanner then assigns each pixel a colour, so a red pixel may be sitting next to a green one, that’s next to a black one, making up your image. Unless you want to increase the size of your image, scan the image at a resolution of 300ppi. If your scanner has a negative setting, use this, otherwise you end up with a positive image. You can turn the image into a negative by using Photoshop or the Gimp and inverting the image.


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