PHOTOSHOP CS4<br />VISUAL DESIGN – 4TH BIMESTER THEORY – 1ST PART <br />
PIXELS<br />PIXEL = PICTURE ELEMENT<br />It’s the smallest unit of picture that can be controlled.<br />The number of distinct colors that can be represented by a pixel depends on the number of bits per pixel (bpp). A 1 bpp image uses 1-bit for each pixel, so each pixel can be either on or off. Each additional bit doubles the number of colors available, so a 2 bpp image can have 4 colors, and a 3 bpp image can have 8 colors:<br />1 bpp, 21 = 2 colors (monochrome)<br />2 bpp, 22 = 4 colors<br />3 bpp, 23 = 8 colors<br />...8 bpp, 28 = 256 colors<br />16 bpp, 216 = 65,536 colors ("Highcolor" )<br />24 bpp, 224 ≈ 16.8 million colors ("Tricolor")<br />
megapixel<br />A megapixel (MP or Mpx) is one million pixels, and is a term used not only for the number of pixels in an image, but also to express the number of image sensor elements of digital cameras or the number of display elements of digital displays. For example, a camera with an array of 2048×1536 sensor elements is commonly said to have "3.1 megapixels" (2048 × 1536 = 3,145,728).<br />
BITMAP AND VECTOR IMAGES<br />BITMAP IMAGES (ALSO RASTER IMAGES) COMBINE DIFFERENT-COLORED PIXELS TO MAKE THE IMAGE. THESE IMAGES ARE RESOLUTION-DEPENDENT. IMAGES SAVED FOR ON-SCREEN DISPLAY HAVE A RESOLUTION OF 72 PPI AND IMAGES FOR PRINT SHOULD HAVE 300 PPI.<br />VECTOR IMAGES ARE NOT CREATED PIXEL BY PIXEL. THEY USE MATHEMATICAL EQUATIONS TO CALCULATE A LINE’S SHAPE. THESE ARE NOT RESOLUTION-DEPENDENT. THEY ARE GREAT FOR ILLUSTRATIONS AND LOGOS THAT NEED TO BE SCALED TO DIFFERENT SIZES.<br />
FILTERS<br />Are usedtoclean up orretouchyourimages, applyspecial art effectsthatgiveyourimagetheappearance of a sketch or pastel painting, and applydistortions and lightingeffects.<br />As withmany PS features, though, youshouldtakecareNOTtoOVERUSEfilters, as toomanyfilters can makeanimage look busyorunprofessional.<br />Eachfilter has a range of settings. Youcan previewthesebeforeyouapplythem.<br />
LIQUIFY FILTER<br />Theliquifyfilterisanotherinterestingfilteryou can applytoimages. It causes theimagetoappearmelted.<br />Usingtjeliquifyfilter, you can push, pull, rotate, reflect, pucker, orbloatanyarea of animage.<br />
watermark<br />Whenshowingothersyourwork, it’s a good idea toapply a watermarktoyourimages so yourintellectualproperty(theimageyouworkedhardtocreate) isprotected.<br />A watermarkis a partly visible messagethatmarkstheimage as belongingtoyou.<br />You can apply a watermarkbyplacingthewatermark in a layerabovetheimageitself and reducingitsopacity.<br />Opacityrefersto a layer’sdegree of transparency.<br />
Gradientmaps<br />Thegradientmapcommandmapsthe tonal range of animagetothecolors of a gradientfill.<br />Tonal rangedescribes theimage’scolors, withthelightest color (usuallywhite) at oneend and thedarkest color (usuallyblack) at theotherend. Every color in between can be expressed in a shade of gray. This tonal rangeisknown as grayscalerange.<br />A gradientfillis a blend of twoor more colors.<br />
Adjustmentlayer<br />As youapply color toanimage, youwillusuallywanttopreserve your original image. <br />Onewayistosave a copyof your original image (thisisalways a good idea)<br />Anadjustmentlayerapplieschangestoyourimagewithoutchangingtheimage’spixelspermanently.<br />
Hue&saturation<br />Hueidentifieseasilynamedcolorssuch as red, orange, and pink and simplyreferstothecolor’sspecific place onthe color wheel.<br />Saturation describes relativeintensityordullness of a color fromtheinsidetotheoutside of thewheel.<br />Forhue, valuesreflectthenumber of degrees of rotationaroundthewheelfromthepixel’s original color.<br />A positivevalueindicatesclockwiserotation.<br />A negativevalueindicatescounterclockwise.<br />Values can rangefrom -180 to +180.<br />In otherwords, whenyouchangehuepositively, blues become more purple, yellows more green and so on.<br />As youdecreasehue, theoppositehappens.<br />
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