DRAPP Image Processing Workshop

DRAPP – ImageProcessing WorkshopCraig Laben – M.S. Imaging ScienceImage Processing Dept. Manager

Agenda Sanborn Image Processing Work Flow– Acquisition, Image Processing, Ortho Production Factors that affect the Image Quality of Acquired Imagery– Time of day/year, weather, flying height Factors that may affect the Appearance of Final Product– Viewing Tool– Monitor/Printers (Plotters) Post Delivery Imagery Radiometric Adjustments––––Global/Local EnhancementsAdobe PhotoshopESRI ArcMAP/ArcGISIrfanview Summary9/1/2017 2013, The Sanborn Map Company, Inc.2

Image Processing Work Flow Imagery Acquisition:– For 2016 DRCOG: 4 planes/sensors, flew 54 missions, at 3different resolutions (3/6/12 inch) over a 4 month period (March4 - June 26), 25,000 images– All imagery is QC’d to make sure it looks good and is issue free,problem images are reflown Color Balance:– Once the entire AOI is accepted, Image Processing Dept. performsa global color balance Brighten imagery, adjust color, reduce haze, no frame-to-frame differences Ortho Production:––––9/1/2017Color balanced imagery is run through a global tiltOrtho-rectifiedMosaicked, cut into tilesFinal contrast/brightness/color adjustments, sharpened 2013, The Sanborn Map Company, Inc.3

Factors that affect Image Quality Try to fly in ideal conditions, not always possible Factors that affect the Image Quality of Acquired Imagery– Time of day – high noon (bright sunshine, no shadows), earlymorning/late afternoon (darker, longer shadows)– Time of year – March, no leaves on trees, grass/vegetationbrown, snow on mountains. End of June, leaves on trees,grass/vegetation bright green, no/less snow.– Weather – Clouds/cloud shadows, overcast vs bright sun, haze,wind (turbulence blur), recent rain vs dry stretch– Flying height – 3-inch flown lower than 6-inch/12-inch The higher you fly, the more the atmosphere affects the imagery– Imagery not as crisp, bluish/purple appearance, hazier– Other factors – glare (roofs, water), smoke (industrial, burning),artifacts (something on camera glass/lens), etc.**DRAPP acquisition parameters were followed as expected9/1/2017 2013, The Sanborn Map Company, Inc.4

Factors affecting Image Quality Factors that may affect the Appearance of Final Product– Personal preference – different people like different color,contrast, brightness, sharpness in their imagery 2016 DRCOG survey results are shown on the next slide– Viewing Tool – different viewing tools display the imagerydifferently (see example next slide) May need to set defaults appropriately to not change the imageryappearance Best to view imagery and make radiometric calls at 100% zoom level– Monitor – different monitors will cause imagery to displaydifferently Sanborn calibrates their monitors so all display imagery similarly Ortho group all has the same brand/model of monitor– Printers (Plotters) – imagery may look OK on screen, but does notlook the same when printed out or plotted Recommend adjusting printer/plotter settings to make prints look good9/1/2017 2013, The Sanborn Map Company, Inc.5

Factors affecting Image Quality Same image opened in Photoshop (left) and ArcMap (right)9/1/2017 2013, The Sanborn Map Company, Inc.6

Personal Preference – 2016 DRCOG survey results 37 participants were asked to rate their preference for both Image Brightnessand Image ColorThere were 4 versions (Sanborn settings 3 modifications) of 3 scenes(urban, rural, mixed) shown at randomParticipants rated the four versions from 1 most preferred to 4 leastpreferredResults showed a pattern, but also a large amount of variabilityBestSecond BestWorstCombine 1 & 2BrightnessTileSanborn SettingsBright1 (Darker)Bright2 (Brighter)Urban - 1873581: 62: 113: 184: 21: 112: 93: 74: 10Mixed - 1852961: 162: 63: 104: 5Rural - 1837601: 132: 123: 124: 0 BestSecondWorstCombine 1 & 2ColorBright3 (Brightness/Contrast)TileSanborn SettingsColor1 (Red)Color2 (Green)1: 32: 93: 64: 191: 172: 83: 64: 6Urban - 1873581: 102: 163: 24: 91: 92: 63: 154: 71: 72: 33: 74: 201:2:3:4:1: 32: 73: 64: 211: 102: 103: 114: 61: 82: 143: 104: 5Mixed - 1852961: 162: 153: 54: 11: 32: 103: 144: 101: 82: 43: 94: 161: 102: 83: 94: 101: 92: 43: 104: 141: 32: 43: 104: 201: 122: 173: 54: 3Rural - 1837601: 182: 83: 104: 11: 62: 113: 114: 91: 42: 43: 84: 211: 92: 143: 84: 6Color3 (Blue)111268Based on these results - Increased brightness/contrast and Sanborn’s colorsettings were used on 2016 DRCOG imagery9/1/2017 2013, The Sanborn Map Company, Inc.7

Post Delivery Imagery Adjustments Final imagery may not be to everyone's preference Users can make radiometric adjustments to final imagery– Can adjust the color, brightness and/or contrast on the deliveredfinal ortho tiles if preferred– Global vs. Local Enhancements – Need to be careful when makingenhancements or could have unwanted consequences If all tiles are not adjusted the same could get a checkerboard appearancewhen mosaicking the tiles (i.e. hard lines between frames) Various image processing tools can be used to enhancethe imagery– Adobe Photoshop – this is what Sanborn uses to make final orthoadjustments and to sharpen the imagery– ESRI ArcGIS – most common package for overlaying vector dataon the ortho imagery (not the best for enhancing imagery)– Irfanview – free tool that can be downloaded online9/1/2017 2013, The Sanborn Map Company, Inc.8

Adobe Photoshop Adjustments Photoshop is a versatile image processing package:– It does not apply any default changes to imagery whenopening/viewing imagery– Allows user to zoom and scroll around imagery easily– Allows user to change the color, brightness & contrast of imagery Can see what changes look like before saving to actual imagery (flicker backand forth)– Allows user to find settings that can be applied to all imagery inthe same way Allows for batch processing – scripts can be created inside to run changes onall imagery– Allows user to make changes for printing/plotting without savingthose changes to the actual ortho TIF files9/1/2017 2013, The Sanborn Map Company, Inc.9

Adobe Photoshop Adjustments Under Image- Adjustments (Levels Color Adjustment)9/1/2017 2013, The Sanborn Map Company, Inc.10

Photoshop Brightness/Contrast Tool Adjust Brightness and/or Contrast (use Preview to flicker Before/After) Brightness will move histogram to left or right Contrast will spread histogram out9/1/2017 2013, The Sanborn Map Company, Inc.11

Photoshop Levels Tool (Adjust Color) Change Channel to color to adjust (from RGB to Red, Green or Blue) Drag center arrow (default 1.0) to left to add that color, right toreduce that color9/1/2017 2013, The Sanborn Map Company, Inc.12

Photoshop Levels Tool (Adjust Color) Here we have removed some green from the original image Info Tab shows the old (left) and new (right) R, G, B numbers– Grey objects (e.g. parking lots) should be close to the same R, G, B number9/1/2017 2013, The Sanborn Map Company, Inc.13

Photoshop – Batch Processing Window- Actions can be used to “record” a series of processing stepsthat can be applied to all imagery (like a script)9/1/2017 2013, The Sanborn Map Company, Inc.14

Photoshop – Batch Processing Actions can then be applied to all imagery in a batch process– Can run on all images in a folder and output to a different folder9/1/2017 2013, The Sanborn Map Company, Inc.15

Photoshop – Saving/Printing “Save” will overwrite existing imagery, “Save As” will make a copy Printer Profile will allow you to enhance print to look good withouthaving to make adjustments to the actual imagery9/1/2017 2013, The Sanborn Map Company, Inc.16

ESRI ArcGIS (ArcMap) Adjustments Default Settings for Viewing Imagery:– For each Image: Right Mouse on Layer- Image Name.tif- Properties Make sure Stretch Type None, Apply Gamma Stretch is unchecked9/1/2017 2013, The Sanborn Map Company, Inc.17

ArcGIS – Contrast/Brightness Tool Image Analysis Tool can be used to adjust Contrast & BrightnessContrast AdjustBrightness Adjust9/1/2017 2013, The Sanborn Map Company, Inc.18

ArcGIS – Contrast/Brightness Tool Enhanced imagery can be saved using the “Export” button– Can save changes to entire AOI or to just what is on screen– Can export various file formats (TIFF, JPEG, etc.)9/1/2017 2013, The Sanborn Map Company, Inc.19

ArcGIS – Contrast/Brightness Tool Stay away from “DRA” (Dynamic Range Adjustment) or any statisticalbased enhancements– These can cause each image to look different and they will not mosaic uniformly– Color adjustments appear to use statistical based stretches (do not recommend)Hard Line9/1/2017 2013, The Sanborn Map Company, Inc.20

Irfanview – Color Corrections Tool Allows user to adjust brightness, contrast and color9/1/2017 2013, The Sanborn Map Company, Inc.21

Irfanview – Color Corrections Tool Can see the before and after as changes are applied – get values9/1/2017 2013, The Sanborn Map Company, Inc.22

Irfanview – Color Corrections Tool Can Batch Process to apply same settings on all imagery9/1/2017 2013, The Sanborn Map Company, Inc.23

Summary Many factors can affect the quality of the imagery Users can modify the color/brightness/contrast if needed Need to be careful to enhance all tiles the same orunwanted affects can happen Under DRAPP 2018 Sanborn can offer additional guidanceon user preferences/enhancements on post delivery ofinitial ortho tiles Questions?9/1/2017 2013, The Sanborn Map Company, Inc.24

–Flying height –3-inch flown lower than 6-inch/12-inch The higher you fly, the more the atmosphere affects the imagery – Imagery not as crisp, bluish/purple appearance, hazier –Other factors –glare (roofs, water), smoke (industrial, burning), artifacts (something on camera glass/lens), etc.