Digital Files File Format Storage Color Temperature

Transcription

1 Digital Files

2 Digital Files File Format Storage Color Temperature

3 PIXELS Pixel = picture element - smallest component of a digital image - MEGAPIXEL

4 1 million pixels = MEGAPIXEL

5 PIXELS more pixels per inch = sharper image and higher resolution pixels are the equivalent of film grain in a digital image. They are the smallest unit of information in a bit-mapped image.

6 PIXELS Penelope Umbrico Unititled (pets and babies) from home decor websites

7 Penelope Umbrico 87 Suns from Flickr - 29 Visible

8 Penelope Umbrico

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10 Thomas Ruff

11 BIT Binary Digit the smallest unit into which the camera (or any computer) is able to digitally divide visual information. the number of distinct colors that can be represented by a pixel depends on the number of bits per pixel (bpp) More BPP = more nuance in color and brightness or density

12 Bit Depth The number of bits used to represent each pixel in an image determining color and tonal range. Greater Bit Depth means greater variety in color and tone.

13 PIXELS AND BIT DEPTH UNDERSTANDING BIT DEPTH better images more control

14 Digital images are usually made up of one, three or four channels RGB has three channels (red, green, blue) CMYK has four (cyan, magenta, yellow, black) K (grayscale image) has one (black)

15 Typical images are 8-bit or 16-bit in imaging software such as Photoshop. In an RGB file, an 8 bit/channel image has an overall bit depth of 24 bits, 16 bits/channel = 48 bits (8 bits x 3 channels = 24 bits) * 8 bit images are 256 colors per channel (2 8 ) and offer (256 x 256 x 256)= 16.7 million colors 16 bit images are 32,000 colors (2 16 ) per channel

16 Digital Camera Resolution - INPUT PPI pixels per inch this describes the digital, pixel resolution of an image. The pixel resolution is the number of pixels per inch in the input digital image.

17 Printer Resolution - OUTPUT DPI - dots per square inch

18 Camera Resolution Maximum number of pixels (PPI) the camera is capable of capturing (e.g. 6-megapixel camera) A megapixel is one million pixels so a 6- megapixel camera is capable of 2000x3000 ppi image. For a maximum print size divide by 300 Megapixel calculator:

19 Image Resolution Image resolution is medium specific Screen (72 ppi) Inkjet Print ( dpi) (Note: The human eye is not capable of discerning pixels in a print which is more than 300dpi)

20 Camera File Format JPEG: Joint Photographic Experts Group - LOSSY compression format - In-camera settings: Basic, Normal, & Fine - Allows more images per megabytes of memory

21 Camera File Format - LOSSLESS TIFF: Tag Image File Format - No compression - Standard in graphics and printing fields RAW: Unprocessed sensor data - Pure Digital Negative - Format can vary between camera manufacturers - most common: DNG / NEF / CR2 - The settings used to take RAW images are saved, but they are not permanently applied to your images until you save them in another format such as JPEG or TIFF.

22 If you shoot using RAW, white balance is not as critical as when shooting JPEG because you can decide the most appropriate white balance when you process the file later. If you shoot using JPEG, the camera is deciding automatically at the time of shooting how to set the white balance and tonal corrections, often clipping the highlights and shadow detail.

23 Tool Bar Full Screen Histogram Zoom level Workflow options Open in Photoshop

24 crop straighten retouch Red eye tool Camera raw preferences Rotate tools

25 C a m e r a R a w i c o n s zoom hand White Balance Color sampler

26 File size: measured in bytes, kilobytes, megabytes, gigabytes File size is how much storage memory your file occupies on your disk and depends entirely upon how much information is in your image. File size is often confused with image size, which is the physical dimension of our image (see next slide)

27 The image size of the image below is 4x5 inches or 360x288 pixels. If you describe an image with its pixel height and width, you are referring to its pixel dimensions

28 File size affects: - the quality of the image - the space the image takes up on your drive - big files can t be easily sent over the internet - time

29 Image Size the physical dimensions of your image, measured in inches, pixels, etc in order to find out how many pixels comprise your image, multiply each length by the ppi for example, an image that is 8 x 10 at 300 ppi is comprised of 2400 pixels by 3000 pixels

30 How big can you print an image? Divide the number of pixels along both dimensions of the picture by the pixel resolution you wish to print How big can you print an image that is 4800 x 6000 pixels at 300 dpi?

31 Interpolation (Resampling) the act of increasing the number of pixels based on the original pixel information and is generally used when trying to make large print from a high quality, but relatively small image.

32 Photoshop offers 5 Interpolation methods. When sampling up, it s best to use Bicubic Smoother, while Bicubic Sharper is best for sampling down.

33 Deselect Resample Image to avoid resizing with Interpolation

34 Memory Cards, Card Readers and External storage devices insert and remove memory cards when the camera is off Remember to eject (move to the TRASH) all external devices including storage and card readers. Eject card reader before removing memory card Upload images using a card reader rather than through the camera

35 BACK UP YOUR IMAGE DATA!!! Nothing is failsafe The best insurance is to back your files up in several places -- hard drives, flash drives, cds, dvds

36 Color - RGB

37 Sergei Prokudin-Gorskii The Emir of Bukhara, 1911

38 Sergei Prokudin-Gorskii Self-Portrait, 1912

39 Florian Maier Aichen Untitled, 2011

40 Color Temperature The colors reflected from a subject are affected by the color of the light source illuminating it.

41 The color of the light is specified by its color temperature in degrees Kelvin.

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43 The color of light changes during different times of the day and at different time of the year.

44 Color Temperature

45 Photographic Color Wheel Each color absorbs its complementary color.

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48 Color Casts A trace of color in all the colors in an image. Neutral color preserves the color of the subjects/objects in the image most accurately to their true color with less or no color cast.

49 Your camera s white balance system removes color casts that would otherwise be created by the color of the light source. It s purpose is to capture images with color that look like they were shot at midday.

50 White Balance Camera Settings Direct Sun Auto White Balance Custom Open Shade Flash Cloudy Incandescent/tungsten Fluorescent