Canon FB630U/FB636U manual Using the Histogram Feature to Adjust Image Contrast

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S T E P 3

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. 35). 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 User’s Guide This page intentionally left blank Where to Look How to Use this GuideAbout the Conventions Used in this Guide Table of Contents Appendices Control Panel Features Scanning Procedures E PGamma Curve Adjusts Image Brightness Plug-in Module CS-U Special FeaturesSee the Results of Adjustments Immediately Dynamic Preview Supports ColorSync 2.0 or higher Auto Tone CorrectionStart Plug-in Module CS-U Installing Plug-in Module CS-UQuick Start Instructions Start the Preview ScanClick the Browser button Set the preferences, magnification and scan mode settingsSpecify the Area of the Image to be Scanned p Select the area to be scanned by clicking and draggingSave the image with the application software, specifying a Scan the Image pClick the Scan button Folder, file name and file formatE P Display Plug-in Module CS-U Control Panel E PE P Operating Procedures Canon PhotoSet the original on the scanner document glass PreviewingClick the Preview button Set Preferences UnitE P Setting Basic Resolution Preview Window Settings Dialog Box E P Preview Window SizeE P Calibration Return to Default SettingsProcedures Select the Prefs menu in the control panelOutput Device Resolution= 360 dpi, Magnification= 100% Set MagnificationE P To Set the Magnification Factor Set the desired magnification factor on the control panelDiffusion Dither Set Scan ModeBlack & White GrayscaleColor 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 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 ImageBlack & White Mode Color/High Definition ModeGrayscale Mode Diffusion DitherHow to Interpret Histograms Using the Histogram Feature to Adjust Image ContrastHow to Adjust Histograms Click the Auto button E P To Adjust a HistogramClick the Histogram button Click the OK buttonAdjusting the Image with Gamma Settings Setting the GammaGamma = GammaContrast Brightness and Contrast SettingsBrightness E P To Adjust the Brightness and Contrast Click the Gamma buttonCRT Type B Adjusting Gamma with the MenuCRT Type a 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 Cause Error MessagesError Message ResponseGlossary Preview ResolutionImage File ScannerIndex P E N D I C E S Canon Customer Care Center Mail support via Canon Computer Systems, IncOE-030AA 0799 CDS Canon Inc