Allow me to propose a lecture idea: "The digital darkroom with GIMP". The lecture will concentrate on photographic techniques using the all mighty GIMP.
Here is the proposed outline for the lecture: Introduction: -------------------------------------------- * The underlying theme of the lecture is that anyone can build a digital darkroom at home using the GIMP as the main image processing software. 99 percent of the process lies in understanding the fundamentals of the digital work flow. The lecture talk about the remaining 1 percent. Background: -------------------------------------------- * For over the past 100 years people have been developing photographic prints using the traditional techniques. In order to understand the digital darkroom it helps to understand the original chemical or "wet" techniques that they are based on. * The digital darkroom does not present a paradigm shift from the traditional darkroom but tries to mimic "wet" processes. * Processes that take a very long time, need dexterity and precision and involve dangerous chemical often take mere minutes in the digital darkroom. * In the traditional darkroom, most of the work centers around the photographic enlarger and the chemical trays. The GIMP is our digital photographic enlarger and chemical trays all rolled into one. All praise the GIMP! Getting your digital studio ready: -------------------------------------------- * Before you even load a photograph into the GIMP you must adjust the gamma settings on your monitor @ http://users.dslextreme.com/~craig.lawson/linux_notes/color.html. Otherwise, what are you really looking at? Is that really black or is my brightness too low? etc. Use xgamma. * Set the color temperature of your monitor to something sensible by comparing it to daylight. * Bit depth 24bpp(2^8x3 channes), 36bpp(2^12x3 channels and 48bpp(2^16x3 channels). http://cinepaint.sourceforge.net/ supports up to 32bits per channel (96bpp!). GIMP supports 24bpp * Understand Resolution. An image on disk does not have a "resolution" per say. Since resolution is actually the picture element density, an image can only have resolution once displayed or printed. Remember that your monitor is a device with the resolution of about 72ppi. Modern inkjets can output about 240 ppi. Since photographic quality inkjets use the CMYK model, every one of the heads can output about 1440ppi and it may take a combination of all 6 colors to produce a shade for --a single point!!!--- then you will have an effective resolution of about 1440/6 = 240ppi. * All of the above is the digital equivalent of making sure your "wet" darkroom has been set up correctly in the most basic terms. * Now you know that the beautiful image you just sent is really beautiful and not just beautiful on *your* screen. The Histogram and Luminosity curve: -------------------------------------------- * The histogram is one of the most important tools that the digital photographic process has introduced. The histogram maps luminosity on the X axis and the amount of picture elements on the Y axis. GIMP allows you to define the upper and lower "cutoff" points for the light and shadow areas of your image. Use it to expand the range the real information in your image has. Note that the "toothcomb" effect is a by-product low-bit images. CC neads an example. * The curve is a wonderful and very powerful tool. The curve allows you to define the function which accepts an image as input and maps every input picture element to an output picture element. The S-curve is our basic starting point to punch up the image. Remember that if the histogram is a paint roller then the curve is a fine art brush. CC needs an example. * The histogram and curve's equivalents in the "wet" dark room include the type or grade of paper you use, the filter dial settings for VC paper and the type, concentration, mixture, temperature and age of your development chemicals. As you can see, it is a very powerful set of tools. Better Black and White: -------------------------------------------- * Take a color image and use the DECOMPOSE function to create separate B/W images with different "feels". Show the three boat-side photos here. * Show how to do duo-tones. Show the tires images here. Note that you can "mark" a luminosity on the curves screen by pointing at it with the cursor on the image. Sharpening your image: -------------------------------------------- * What is Unsharp Mask? Digitizing introduces blurr. We can artificially try and regain the illusion of sharpness. Controlling contrast: -------------------------------------------- * Ansel Adams liked to use Grade 2 paper. The choice of contrast can change the "spirit" of a photograph. * Local Contrast Enhancement, Amount 20% Radius 25 (will the next GIMP give us bigger radius es?) Threshold 0. Show Venice photos here. * Contrast Masking and digital blending with bracketed images. Show Chertaldo for contrast masking. Digital blending very difficult indeed. You read it all? Like the captain aboard the spaceship CATS attacked said: "What you say?". -- "Cut your own wood and it will warm you twice" Regards, Yoni Rabkin Katzenell -------------------------------------------------------------------------- Haifa Linux Club Mailing List (http://www.haifux.org) To unsub send an empty message to [EMAIL PROTECTED]
