Canon FB636U Using the Histogram Feature to Adjust Image Contrast, How to Interpret Histograms

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S T E P 4

Using the Histogram Feature to Adjust Image Contrast

The data comprising an image contains a variety of brightness settings ranging from shadows to highlights. These settings are represented in Plug-in Module CS-U by values ranging between 0 and 255. The difference in these values determines the image’s contrast. To show how much of the image data falls into each brightness setting, Plug- in Module CS-U contains a Histogram feature that shows this data distribution clearly. With the Histogram you can adjust the level of shadows and highlights to achieve beautiful tones with the best possible contrast.

Hint

• You may not alter the histogram for images scanned in the Color mode when ColorSync is active or for images scanned in the Black & White mode.

•You can use the Histogram only with grayscale, color or high definition color images.

How to Interpret Histograms

You can select the entire image or specify an area for which a histogram will be generated. The height of the peaks of the histogram is directly related to the volume of data with the corresponding value.

Portion with

Highlights

Portion with

Shadows

Entire Image

How to Adjust Histograms

Distribution of data with a bias toward highlights.

Distribution of data with a bias toward shadows.

Distribution of data widely distributed between shadows and highlights.

To change the contrast in an image, the distribution of data between shadows and highlights can be adjusted by dragging the shadow and highlight marks at the bottom of the histogram. All of the data lying to the outside (left) of the shadow mark is changed to a zero value and all of the data lying to the outside (right) of the highlight mark is changed to a 255 value. The examples below show adjustments to improve the contrast. Use the Auto setting to adjust the Histogram for most jobs (p. 41). The graphs below show images adjusted with the Auto setting.

IMAGE Image with a bias			IMAGE Image with a bias			IMAGE Image with well
1	toward highlights		2	toward shadow	3		distributed data

Move the shadow mark	Move the highlight mark	Move both the shadow and
toward the highlight end.	toward the shadow end.	highlight marks inward.

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Contents Users Guide How to Make Best Use of the Manuals Getting StartedWhere to Look How to Use this GuideAbout the Conventions Used in this Guide Table of Contents Adjusting and Editing Scanned Images AppendicesControl Panel Features Scanning Procedures Adjusting and Editing Scanned ImagesE P Scanning Preparations pPlug-in Module CS-U Special Features See the Results of Adjustments Immediately Dynamic PreviewGamma Curve Adjusts Image Brightness Supports ColorSync 2.0 or higher Auto Tone CorrectionInstalling Plug-in Module CS-U Quick Start InstructionsStart Plug-in Module CS-U Start the Preview ScanSet the preferences, magnification and scan mode settings Specify the Area of the Image to be Scanned pClick on the Browser button Select the area to be scanned by clicking and draggingScan the Image p Click on the Scan buttonSave the image with the application software, specifying a Folder, file name and file formatE P E P Installing Plug-in Module CS-UOperating Environment E P Procedures Click the Install the Software buttonClick the Yes button to start the installation E P E P Scanning Preparations Display Plug-in Module CS-U Control Panel ButtonsAdobe PhotoDeluxe E P Operating ProceduresAdobe Photoshop Set the original on the scanner document glass PreviewingClick on the Preview button Set Preferences UnitE P Setting Basic Resolution Preview Window Settings Dialog Box E P Preview Window SizeReturn to Default Settings E P CalibrationSelect the Prefs menu in the control panel Select the desired option from the pull-down menuOutput Device Resolution= 360 dpi, Magnification= 100% Set MagnificationE P To Set the Magnification Factor Set the desired magnification factor on the control panelSet Scan Mode Black and White Mode LineBlack and White Mode Diffusion Dither Grayscale Mode 8-bitColor Mode 24-bit High Definition ColorTo Set the Scan Mode Select the scan mode that you wantVerify Image Before Scanning To Verify the ImageE P Scanning Scan Area Settings Position the pointer in the preview windowTo Zoom ZoomingSelect the area you want to enlarge with the zoom function Click on the Zoom In button To return to normal view, click the Zoom Out buttonTo Initiate the Scan ScanningSpecify the Scan Area Saving Scanned Images To Save an ImageColor Mode Grayscale ModeBlack & White Mode Diffusion DitherHow to Interpret Histograms Using the Histogram Feature to Adjust Image ContrastHow to Adjust Histograms E P To Adjust a Histogram Click on the Histogram buttonClick the Auto button Click on the OK buttonAdjusting the Image with Gamma Settings Setting the GammaGamma = GammaContrast Brightness and Contrast SettingsBrightness Click the gamma button E P To Adjust the Brightness and ContrastClick the OK button Adjusting Gamma with the Menu CRT Type aCRT Type B CRT Type CE P To Change the Gamma Value Settings Click the radio button for Menu SettingAdjusting the Gamma Value to Match the Display Gamma Value SettingsSending Output to a Printer Slider Tone Curve Settings Manipulating the GraphE P To Edit the Tone Curve Auto Tone Correction ColorSync To Activate the ColorSync FunctionDescreen ProcedureOpen the Image menu and select Descreen To Set the Threshold Value Set the threshold value in the Control PanelSaving / Recalling Settings To Save Settings in a Settings FileE P To Recall a Settings File Editing Scanned Images Many special effects may be achieved with filtersOptical and Enhanced Resolutions Matching Scan Resolution to PurposeScanning Techniques Functional Specifications SpecificationsSystem Requirements Problem TroubleshootingClicked on the Plug-in Module CS-U control panel Scan button cannot be selected Error Messages Error MessageCause ResponseGlossary Resolution Image FilePreview ScannerIndex P E N D I C E S Canon Customer Support Help Desk HelpdeskOE-030AA 0799 CDS Canon Inc