First create a photoshop document the same size as your transparencies. For mine it is an 8x10inch. If you would like to use the same scale as me, download this image. In photoshop use transform to scale the image to fill the entire sheet.
Custom Inkjet Negatives
Printing multiple layers over each other inevitably has one result: the accumulating layers make your print darker and darker. To solve this problem we need to make the inkjet transparencies darker (more opaque to uv light) and choose suitable exposure times. Rather than arbitrarily darkening our negatives, we will be measuring and calibrating them to achieve a custom inkjet transparency scale so that our prints get the perfect balance of correct exposure and long scale. Before you continue you may want to see the previous sections starting with the advanced introduction if you have not.
- Photo Quality Inkjet Printer
- Inkjet Transparencies
- Image editing software like Photoshop or GIMP
- Flatbed Scanner
- A spreadsheet program like Excel
- A tremendous amount of Patience!
Supplies for Custom Inkjet Negatives:
Digital images have 256 values of gray. This is far to large a number of values to test. We will simplify the full scale into a smaller number of values by using the ideas of Ansel Adam's famous zone system. The zone system divides the scale into 10 discrete values and uses (mostly) roman numerals, with zone I being just above absolute black, zone V being middle gray, and zone X being absolute white. Each zone is supposed to correspond to 1 stop of exposure in a camera.
When it comes to a computer or a print, the precise values of zones are largely subjective. To the right is a table of zones, half zones, and their corresponding rgb values which I created by dividing a scale into equal parts and measuring each area's average value. (I used regular numbers rather than roman numerals to avoid clutter) I will be using this scale in the following tutorials, however any scale of values will work.
Making the test Negative
The first thing we will need is an unaltered test inkjet negative that includes a scale and an image. The scale will be used to measure numerically, and the image to get a subjective idea of what the scale translates to in an actual print. Search your photographs for an image with a balance of darks grays and highlights. I'll be using an image of myself playing a guitar.
Paste your image into a new layer and scale it to take up approximately 1/2 the page. If it is a horizontal image, simply rotate the image 90 degrees.
Select a portion of the scale and use transform to flip the selected area vertically. Do not simply use invert! That will alter the values of the scale and make any measurements meaningless.
Having two scales will help us get better measurements later in case the emulsion coating is uneven from one side to another.
Add numbers to the sides of the values so you can remember which one is which. It does get confusing after a while! (Note zone '0' is twice as big as the other zones. There is no zone '0.5', because the counting starts at 1)
Flip the image horizontal before printing
Save the photoshop file! We will need this exact negative again later on.
Before printing, invert the image. Note that by doing so the actual rgb values of each zone change, for example rgb0 becomes rgb255 and an rgb value of 4 becomes 251.
Print onto a transparency sheet. Use your printer's glossy paper setting and the highest quality. You may wish to save a preset called "gum_negative" if your printer's software allows it, and use that preset for every other negative you print.