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Aperture  Opening in the lens  Aperture  f-number or stop  = focal length/Aperture diameter  Each stop represents either half or double the amount.

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Presentation on theme: "Aperture  Opening in the lens  Aperture  f-number or stop  = focal length/Aperture diameter  Each stop represents either half or double the amount."— Presentation transcript:

1 Aperture  Opening in the lens  Aperture  f-number or stop  = focal length/Aperture diameter  Each stop represents either half or double the amount of light exposing the film or chip

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3 The circle of confusion is defined as the largest blur spot that is indistinguishable from the point source that is being rendered. Stated more simply, it is the limit at which we start noticing that things are getting blurry. Based on this definition, the circle of confusion should more appropriately be called the circle of “maximum” confusion (or “least” confusion if you are a glass half full person).

4 Where to Focus  If you are focused on a subject you will have roughly twice as much depth of field behind the subject than in front of it  A rule of thumb when shooting is to focus on the subject one third the distance from the closer to the farther object where to focus

5 Exposure Range/Contrast Range  Our eyes adjust to scenes way better than video  In video you have to either choose between detail in the shadows or detail in the highlight area  Video anywhere between 5 to 45 stops of contrast range

6 GAMMA SETTING  Was used to compensate for the difference between a CRT monitors which were incapable of linear image reproduction—in which output brightness was directly proportional to input signal level. Gamma was needed so that shadow areas wouldn’t be too dark and bright areas wouldn’t wash out  This isn’t necessary with digital monitors  Gamma curves can be used to capture a greater range of scene brightness than was possible in analog

7 Gamma  In photography and motion picture film gamma is a number that expresses the contrast of a recorded image as compared to an actual scene  1:1 contrast would be if the scene was re-created perfectly .55:1 Motion Picture Negative  2:1 is the final projection—twice what is seen in nature  In video gamma can be used as a creative tool to capture a greater range of a scene  High gamma setting: Can compress and stretch the blacks  Low gamma setting can create a super high contrast image

8 Contrast: Gamma

9 Adjusting the knee

10 Histogram

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12 Waveform Monitor

13 Reflective vs. Incident Light Meter

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15 Gray Card

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17 Pixels and Resolution  The digital video frame is made up of a lattice or grid of pixels  HD Formats have a higher resolution (more pixels)  Our ability to judge resolution is related to how large the image appears  How big is the screen? From how far away are you viewing it?  In most living room viewing conditions consumers can’t always see the difference between 1080p and 720p  In theatrical distribution it is debatable whether audiences can see a difference between 1080p 2k about 2048X1080 and 1080p 4k 4096X2160. This depends on the screen size and the audience member’s distance from the screen

18 Bit Depth  Resolution can be improved by measuring the brightness of each pixel more precisely  Eight bit systems can distinguish between 256 different brightness values for each pixel  256 shades of red, green and blue—millions of colors  16 bit systems yield 65,536 gradations of each color. The more gradations, the finer the detail.  Greater bit depth allows better color correction and the ability to recover shadow and highlight detail.

19 Resolution and Sharpness  The resolution of a video image refers to its ability to reproduce fine detail. Often this allows an image to look sharp to the eye.

20 Still image and Video  DPI or PPI (dots per inch and pixels per inch) refer to the size of a single digital image.  This is irrelevant in Video. The numbers in video only refer to the dimensions.  1,024 × 576 pixels | 1,280 × 720 pixels. 1,024 × 576 pixels | 1,280 × 720 pixels.  Full resolution ‎ (1,920 × 1,080 pixels Full resolution ‎ (1,920 × 1,080 pixels

21 Different formats  Quicktime: Apple  MPEG-4: container file format from Quicktime. H.264  Windows Media: Microsoft container format  MXF: Material Exchange Format: Used in cameras and editing systems  AAF and OMF: Advanced Authoring Format: open exchange between different applications or systems  XML Interchange format: a tool used to describe data using plain text, so that it can be transferred from one NLE to another  DPX: Digital Picture exchange is a nonproprietary container file for uncompressed images

22 Data Exchange  A digital movie file is made up of video audio and metadata packaged inside a container or wrapper  The video may be uncompressed or compressed with one of many possible codecs H.264, DV, DVCPRO, HD

23 Artifacts  A compression artifact (or artefact ) is a noticeable distortion of media (including images, audio, and video) caused by the application of lossy data compression.images, audio, and video) caused by the application of lossy data compression.

24 What is Moiré  Moiré pattern occurs when a scene or an object that is being photographed contains repetitive details (such as lines, dots, etc) that exceed the sensor resolution. As a result, the camera produces a strange- looking wavy pattern as seen  Read more: t-is-moire#ixzz2hFKzfPFsLooks like vibrating of the actual image t-is-moire#ixzz2hFKzfPFs  A mathematical error that occurs when you are down sampling—not using all of the sensor

25 Compression  intraframe: Compressing within a frame: DCT: discrete cosine transform or wavelet  Interframe: compresses several frames in a group

26 Constant and Variable Bit Rates  CBR  VBR: efficient data It provides more data when you need it and less when you don’t. This can result in fewer artifacts and smaller file sizes.

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