flame. I'm in favor.
flame. When can you give it? flame. ;) On Wed, 11 Feb 2004, Yoni Rabkin Katzenell wrote: > > 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?". > > -- Orr Dunkelman, [EMAIL PROTECTED] "Any human thing supposed to be complete, must for that reason infallibly be faulty" -- Herman Melville, Moby Dick. Spammers: http://vipe.technion.ac.il/~orrd/spam.html -------------------------------------------------------------------------- Haifa Linux Club Mailing List (http://www.haifux.org) To unsub send an empty message to [EMAIL PROTECTED]
