Notes on Processed Spectral Images

This page introduces, enumerates, and briefly defines the processed spectral image types, GIF animations, and PowerPoint presentations produced by the two phases of the Livingstone Spectral Imaging Project (2010-13, 2013-17).

Introduction
Overview List of Spectral Images Types
          1. Processed Spectral Images
          2. GIF Animations and PowerPoint Presentations
          3. Notes on a Few Unusual Imaging Cases
Processed Spectral Image Descriptions
GIF Animations and PowerPoint Presentations
Notes on a Few Unusual Imaging Cases

Introduction    Top

Our work on the critical editions of Livingstone’s 1870 and 1871 Field Diaries and the Letter from Bambarre has resulted in a range of processed spectral images. Below, we enumerate the processed spectral image types, GIF animations, and PowerPoint presentations developed by our scientists (Roger Easton, Keith Knox, and Caroline Houston) in close collaboration with our scholars (Adrian S. Wisnicki, Megan Ward, Debbie Harrison, and Kate Simpson) to address our research goals. In a separate section of the site, we also out set out the objectives of the animated spectral images (ASIs) developed by one of our junior project scholars (Ashanka Kumari).

A natural image of David Livingstone's 1870 Field Diary, second gathering (Livingstone 1871b:LXXVIII). Copyright National Library of Scotland. Creative Commons Attribution-NonCommercial 3.0 Unported (https://creativecommons.org/licenses/by-nc/3.0/).
A spectral image of David Livingstone's 1870 Field Diary, second gathering (Livingstone 1871b:LXXVIII). Processed to minimize ink bleed through from the verso of the page. Copyright National Library of Scotland. Creative Commons Attribution-NonCommercial 3.0 Unported (https://creativecommons.org/licenses/by-nc/3.0/).
A spectral image of David Livingstone's 1870 Field Diary, second gathering (Livingstone 1871b:LXXVIII). Processed to maximize and distinguish ink bleed through from the verso of the page. Copyright National Library of Scotland. Creative Commons Attribution-NonCommercial 3.0 Unported (https://creativecommons.org/licenses/by-nc/3.0/)
A spectral image of David Livingstone's 1870 Field Diary, second gathering (Livingstone 1871b:LXXVIII). Processed to enhance and reveal the extent of staining. Copyright National Library of Scotland. Creative Commons Attribution-NonCommercial 3.0 Unported (https://creativecommons.org/licenses/by-nc/3.0/).
A spectral image of David Livingstone's 1870 Field Diary, second gathering (Livingstone 1871b:LXXVIII). Processed to highlight staining while also showing the relationship of text to underlying page topography. Copyright National Library of Scotland. Creative Commons Attribution-NonCommercial 3.0 Unported (https://creativecommons.org/licenses/by-nc/3.0/).
A spectral image of David Livingstone's 1870 Field Diary, second gathering (Livingstone 1871b:LXXVIII). Processed to reveal underlying page topography. Copyright National Library of Scotland. Creative Commons Attribution-NonCommercial 3.0 Unported (https://creativecommons.org/licenses/by-nc/3.0/).
Six of the eighteen processed spectral images available for a single page of the 1870 Field Diary (Livingstone 1871b:LXXVIII). Copyright National Library of Scotland. Creative Commons Attribution-NonCommercial 3.0 Unported. The images include (left to right by row, or top to bottom on mobile devices) a natural light image plus images processed to 1) minimize ink bleed through from the verso of the page, 2) maximize and differentiate ink bleed through from the verso, 3) enhance and reveal the extent of staining, 4) highlight staining while also showing the relationship of text to underlying page topography and 5) reveal underlying page topography.

For the second phase of the Livingstone Spectral Imaging Project (2013-17), we have repurposed a handful of processed images from the first phase (2010-13), as review showed that some images previously developed to recover faded text could also illuminate material history. These repurposed images are marked with two asterisks (**) in the list below. The other images from the first project phase are marked with a single asterisk (*). Images and other items not marked with any symbol are a direct result of the second project phase.

For each item, we provide 1) the short name by which we refer to the image type, animation, or presentation throughout our critical materials, 2) the original image name suffix (if available), which can contain unique processing information related to image creation, 3) a short description (provided by our scientists) of the underlying processing technique, 4) a list of material manuscript features for which the given image type proves particularly suited (images related to 1870 Field Diary only), and 5) the name of the scientist(s) who led the relevant spectral image processing.

For further analysis of the images and the implications for our understanding of the 1870 Field Diary manuscript, users should consult our six-part essay on The State of the Manuscript, especially parts III, IV, and V.

Looping GIF animation of a sequence of pages (1870i:XXXIX-LV [v.1], odd-numbered pages only) that demonstrate the process of staining across these pages. The stain spreads from the lower-left (lower-numbered pages) to cover nearly the whole left side of the page (higher-numbered pages). Copyright National Library of Scotland. Creative Commons Attribution-NonCommercial 3.0 Unported (https://creativecommons.org/licenses/by-nc/3.0/).
Looping GIF animation of a sequence of pages (1870i:XXXIX-LV [v.1], odd-numbered pages only) that demonstrate the process of staining across these pages. The stain spreads from the lower-left (lower-numbered pages) to cover nearly the whole left side of the page (higher-numbered pages). Copyright National Library of Scotland. Creative Commons Attribution-NonCommercial 3.0 Unported

 

Overview List of Spectral Images Types    Top

I. Processed Spectral Images    Top

color**

color raking

IC1_(liv_000204_0001_trans)

IC2_(liv_000204_0001_trans)

IC3_(liv_000204_0001_trans)

IC4_(liv_000204_0001_trans)

IC5_(liv_000204_0001_trans)

ICA_pseudo_(liv_000204_0001_trans)

ICA_pseudo_(liv_000205_0032_trans)

intercept*

PCA_pseudo_(liv_000205_0032_stats)

PCA_pseudo_(liv_000205_0034_stats)

pca###r*

pca###r_adapThresh*

pca###r_adapThresh_multiply*

pca###r_pcolor*

pseudo_0505-0780**

pseudo_0780*

pseudo_0780_by_0940*

pseudo_0940_by_0592

pseudoBY_0940_by_0592

pseudoratio_0505-0780*

RAIPratio*

raking_irdiff**

raking_irdiff_mockup

RAPRratio*

RARR*

ratio_by_940**

red_green

RIRL*

sharpie_0505-0780**

sharpieratio_0505-0780*

 

II. GIF Animations and PowerPoint Presentations    Top

color_raking

flipbook

overlaid

[various]

 

III. Notes on a Few Unusual Imaging Cases    Top

liv_000200_0006_PCA_pseudo_(liv_000205_0034_stats)

liv_000202_0004

liv_000202_0004_color

liv_000204_0001 and liv_000204_0002

liv_000204_0001_PCA_pseudo_(liv_000205_0034_stats)

 

* = developed for the first phase of the Livingstone Spectral Imaging Project (2010-13), which included the development of critical editions of Livingstone’s Letter from Bambarre and 1871 Field Diary.

** = developed for the first phase of the Livingstone Spectral Imaging Project (2010-13) and repurposed for the second phase (2013-17), which includes the development of critical editions of Livingstone’s 1870 Field Diary and select 1871 manuscripts.

Note: In the interests of creating a uniform data set, we have (with a few exceptions) applied each processing technique to every page of the 1870 Field Diary, although in some cases we developed the techniques to address research questions related only to specific pages of the diary.

 

Processed Spectral Image Descriptions    Top

color**

Short name: color

Original file name suffix: color

Processing description: This image approximates a natural light image and is created using registered, 16-bit flattened TIFF images captured under five visible illuminant bands: royal blue (450 nm), cyan (505 nm), green (535 nm), amber (592 nm), and red (638 nm). A set of linear formulae is used to calculate calibrated color values from the five bands at each pixel position, and each image is output using a CIE L*a*b color space. The white swatch of the ColorChecker24 placed in each of the 5 input image files is used to establish the white point.

Aspects of manuscript enhanced: Preliminary composition and additions, reinking and revision, impressions, torn pages, brown stains, red stains, other material features

Lead Scientist: Knox

color_raking

Short name: color_raking

Original file name suffix: color_raking

Processing description: Blending of a full-color, natural light image with a raking light image that shows page topography. The raking light image is the difference of the two infrared (940 nm) raking images, divided by the regular reflectance infrared (940 nm) image. By blending the two images together, the condition of the handwriting can be related to the topography of the page.

Aspects of manuscript enhanced: Relationship of text to topography, folds, impressions, holes

Lead Scientist: Knox

IC1_(liv_000204_0001_trans)

Short name: IC1

Original file name suffix: cal_trans_DLC297d_20-17-18-19_001r_0_cube_12bands_text_IC1

Processing description: First band generated from the 12 independent components evaluated using the transformation determined from the spectral images of liv_000204_0001 (originally called: DLC297d_20-17-18-19_001r).

Aspects of manuscript enhanced: Primary printed texts, pre-composition

Lead Scientist: Easton

IC2_(liv_000204_0001_trans)

Short name: IC2

Original file name suffix: cal_trans_DLC297d_20-17-18-19_001r_0_cube_12bands_text_IC2

Processing description: Second band generated from the 12 independent components evaluated using the transformation determined from the spectral images of liv_000204_0001 (originally called: DLC297d_20-17-18-19_001r).

Aspects of manuscript enhanced: Handwritten additions

Lead Scientist: Easton

IC3_(liv_000204_0001_trans)

Short name: IC3

Original file name suffix: cal_trans_DLC297d_20-17-18-19_001r_0_cube_12bands_text_IC3

Processing description: Third band generated from the 12 independent components evaluated using the transformation determined from the spectral images of liv_000204_0001 (originally called: DLC297d_20-17-18-19_001r).

Aspects of manuscript enhanced: Primary printed texts, handwritten additions, pre-composition, folds, impressions, torn pages, holes, red stains

Lead Scientist: Easton

IC4_(liv_000204_0001_trans)

Short name: IC4

Original file name suffix: cal_trans_DLC297d_20-17-18-19_001r_0_cube_12bands_text_IC4

Processing description: Fourth band generated from the 12 independent components evaluated using the transformation determined from the spectral images of liv_000204_0001 (originally called: DLC297d_20-17-18-19_001r).

Aspects of manuscript enhanced: Primary handwritten texts, pre-composition, reinking and revision, page discolor, red stains, miscellaneous singular stains, invisible stains

Lead Scientist: Easton

IC5_(liv_000204_0001_trans)

Short name: IC5

Original file name suffix: cal_trans_DLC297d_20-17-18-19_001r_0_cube_12bands_text_IC5

Processing description: Fifth band generated from the 12 independent components evaluated using the transformation determined from the spectral images of liv_000204_0001 (originally called: DLC297d_20-17-18-19_001r).

Aspects of manuscript enhanced: Primary handwritten texts, pre-composition, reinking and revision, invisible stains

Lead Scientist: Easton

ICA_pseudo_(liv_000204_0001_trans)

Short name: ICA_pseudo_1

Original file name suffix: cal_trans_DLC297d_20-17-18-19_001r_0_cube_12bands_text_ICA_R1G2B4

Processing description: Pseudocolor image created from three bands evaluated by independent component analysis using the transformation determined for liv_000204_0001 (originally called: DLC297d_20-17-18-19_001r). IC band 1 was placed in the red channel, IC band 2 in the green, and IC band 4 in the blue.

Aspects of manuscript enhanced: Primary handwritten texts, handwritten additions, page discolor, brown stains, red stains

Lead Scientist: Easton

ICA_pseudo_(liv_000205_0032_trans)

Short name: ICA_pseudo_32

Original file name suffix: cal_trans_NLS10703_052_018v_bands01+03+05+07+09+11_cal_text_ICA_R1G5B6

Processing description: Pseudocolor image created from three bands evaluated by independent component analysis of six original bands using the ICA transformation determined for liv_000205_0032 (originally called: NLS10703_052_018v). IC band 1 was placed in the red channel, IC band 5 in the green, and IC band 6 in the blue.

Aspects of manuscript enhanced: Preliminary composition and additions, page discolor, the big stain, miscellaneous singular stains

Lead Scientist: Easton

intercept*

Short name: intercept

Processing description: Infrared images (700 nm - 940 nm) are fit to a best straight line on a pixelwise basis. This generates "slope" and "intercept" images.

Aspect of manuscript enhanced: Blotted text

Lead Scientist: Knox

PCA_pseudo_(liv_000205_0032_stats)

Short name: PCA_pseudo_32

Original file name suffix: cal_stats_NLS10703_052_018v_bands01-12_text_PCA_R-1G-1B3

Processing description: Pseudocolor image created from first and third bands evaluated by principal component analysis using the statistics determined from 12 reflectance bands of liv_000205_0032 (originally called: NLS10703_052_018v). The files were rendered using a linear mapping that discarded the values for the top 2% and bottom 2% of the pixels for the entire image.

Aspects of manuscript enhanced: Page discolor, the big stain

Lead Scientist: Easton

PCA_pseudo_(liv_000205_0034_stats)

Short name: PCA_pseudo_34

Original file name suffix: cal_stats_NLS10703_054_019v_bands01-12_text_PCA_R1G5B6

Processing description: Pseudocolor image created from three bands evaluated by principal component analysis using the statistics determined from 12 reflectance bands of liv_000205_0034 (originally called: NLS10703_054_019v). The files were rendered using a linear mapping that discarded the values for the top 2% and bottom 2% of the pixels for the entire image.

Aspects of manuscript enhanced: Page discolor, the big stain

Lead Scientist: Easton

pca###r*

Short name: pcar###r

Variants of file name suffix: pca321r, pca321r_1, pca321r_2, pca421r, pca621r, pca721r

Processing description: Grayscale image that is extracted from a single channel of the corresponding pca###r_pcolor image. Note: the ### indicates the principal component bands used.

Lead Scientist: Easton/Houston

pca###r_adapThresh*

Short name: pca###r_adapThresh

Variant of file name suffix: pca321r_adapThresh

Processing description: Adaptive threshold. A bitonal image (black, white) is calculated from a gray-scale image where the gray value used to threshold is based on the local statistics, i.e., it "adapts" to the local situation. Note: the ### indicates the principal component bands used.

Lead Scientist: Easton/Houston

pca###r_adapThresh_multiply*

Short name: pca###r_multiply

Variants of file name suffix: pca321r_adapThresh_multiply, pca321r_1_adapThresh_multiply, pca321r_2_adapThresh_multiply, pca421r_adapThresh_multiply, pca621r_adapThresh_multiply, pca721r_adapThresh_multiply

Processing description: Grayscale image that is the result of the multiplication of the thresholded grayscale image and the corresponding pca###r image. Note: the ### indicates the principal component bands used.

Lead Scientist: Easton/Houston

pca###r_pcolor*

Short name: pcar_pcolor

Variants of file name suffix: pca321r_pcolor, pca421r_pcolor, pca621r_pcolor, pca721r_pcolor

Processing description: Psuedocolor image made up of principal component bands with the hue angle rotated. Note: the ### indicates the principal component bands used.

Lead Scientist: Easton/Houston

pseudo_0505-0780**

Short name: pseudo_v1

Original file name suffix: pseudo_0505-0780

Processing description: 505 nm and 780 nm wavelengths are combined in a no-veil pseudocolor image with the 780 in the red separation and the 505 in the blue and green separations.

Aspects of manuscript enhanced: Primary handwritten texts, preliminary composition and additions, reinking and revision, red stains

Lead Scientist: Knox

pseudo_0780*

Short name: pseudo_v2

Processing description: 505 nm and 780 nm wavelengths from one side of a page are put into the red and green separations, respectively. The 505 nm wavelength image of the reverse side is reversed and aligned with the front side, then placed in the blue separation.

Aspect of manuscript enhanced: Primary handwritten texts and overtexts

Lead Scientist: Knox

pseudo_0780_by_0940*

Short name: pseudo_v3

Processing description: 505 nm and 780 nm wavelengths from one side of a page are divided by the 940 nm wavelength and put into the red and green separations, respectively. The 505 nm wavelength image of the reverse side is divided by the 940 nm wavelength, reversed and aligned with the front side, then placed in the blue separation.

Aspect of manuscript enhanced: Primary handwritten texts and overtexts

Lead Scientist: Knox

pseudo_0940_by_0592

Short name: pseudo_v4

Original file name suffix: pseudo_0940_by_0592

Processing description: Pseudocolor image that combines images from the front and back sides of the given page. The image on each side is the ratio of an infrared image (940 nm) with a red image (592 nm). The ratio sharpens the smeared handwriting. The pseudocolor combination of the two sides separates the handwriting from the smearing from the other side, by rendering the two sides in different colors (red and green).

Aspects of manuscript enhanced: Blotting and bleed through

Lead Scientist: Knox

pseudoBY_0940_by_0592

Short name: pseudo_v4_BY

Original file name suffix: pseudoBY_0940_by_0592

Processing description: Pseudocolor image that combines images from the front and back sides of the given page. The image on each side is the ratio of an infrared image (940 nm) with a red image (592 nm). The ratio sharpens the smeared handwriting. The pseudocolor combination of the two sides separates the handwriting from the smearing from the other side, by rendering the two sides in different colors (blue and yellow).

Aspects of manuscript enhanced: Blotting and bleed through

Lead Scientist: Knox

pseudoratio_0505-0780*

Short name: pseudoratio

Processing description: 505 nm and 780 nm wavelengths are divided by the 940 nm wavelength and then combined in a standard pseudocolor image.

Aspect of manuscript enhanced: Primary handwritten texts and overtexts

Lead Scientist: Knox

RAIPratio*

Short name: RAIPratio

Processing description: Left and right raking infrared images are divided by the non-raking 940 nm image and used in a standard pseudocolor image.

Aspect of manuscript enhanced: Topography

Lead Scientist: Knox

raking_irdiff**

Short name: raking

Original file name suffix: raking_irdiff

Processing description: Left and right raking images in infrared are differenced, divided by the non-raking 940 nm wavelength, then linearly stretched to fit 6 standard deviations from white to black.

Aspects of manuscript enhanced: folds, impressions, torn pages, holes

Lead Scientist: Knox

raking_irdiff_mockup

Short name: raking_mockup

Original file name suffix: pseudo_raking_irdiff

Processing description: Independent components analysis image, derived from 12 wavelength bands, which gives a similar appearance to raking_irdiff images (created by differencing left and right raking images). These images are created instead of raking_irdiff images in those instances where raking images were not captured during original imaging.

Aspects of manuscript enhanced: folds, impressions, torn pages, holes

Lead Scientist: Knox

RAPRratio*

Short name: RAPRratio

Processing description: Right raking blue and infrared images are divided by the non-raking 940 nm image and used in a standard pseudocolor image.

Aspect of manuscript enhanced: Relationship of text to topography

Lead Scientist: Knox

RARR*

Short name: RARR

Processing description: Right raking blue image is divided by the right raking infrared image and then linearly contrast stretched.

Aspect of manuscript enhanced: Primary handwritten texts and overtexts

Lead Scientist: Knox

ratio_by_940**

Short name: spectral_ratio

Original file name suffix: ratio_by_940

Processing description: 450 nm, 592 nm and 850 nm wavelengths are divided by the 940 nm wavelength, stretched to fit 6 standard deviations from white to black and put into the red, green and blue separations respectively.

Aspects of manuscript enhanced: Primary handwritten texts and overtexts, preliminary composition and additions

Lead Scientist: Knox

red_green

Short name: red_green

Original file name suffix: […]_Red_[…]_Green_color

Processing description: Pseudocolor image that combines the color images of both sides of the given page. The reverse side is aligned with the front side and the two color images are blended together, emphasizing the red separation of the front and the green separation of the reverse side.

Aspects of manuscript enhanced: Blotting and bleed through, red stains

Lead Scientist: Knox

RIRL*

Short name: RIRL

Processing description: Left and right raking infrared images are differenced and linearly contrast stretched.

Aspect of manuscript enhanced: Topography

Lead Scientist: Knox

sharpie**

Short name: sharpie

Original file name suffix: sharpie_0505-0780

Processing description: 505 nm and 780 nm wavelengths are combined in a no-veil pseudocolor image with the 780 in the red separation and the 505 in the blue and green separations. The sharpie image is made by linearly stretching the difference of the red and blue separations of the pseudocolor image.

Aspects of manuscript enhanced: Primary handwritten texts, handwritten additions, miscellaneous singular stains

Lead Scientist: Knox

sharpieratio_0505-0780*

Short name: sharpieratio

Processing description: 505 nm and 780 nm wavelengths are divided by the 940 nm wavelength and then combined in a standard pseudocolor image. The sharpie image is made by linearly stretching the difference of the red and blue separations of the pseudocolor image.

Aspects of manuscript enhanced: Primary handwritten undertexts

Lead Scientist: Knox

 

GIF Animations and PowerPoint Presentations    Top

color_raking

Original file name suffix: color_raking

Processing description: GIF animation of a blending of a full-color, natural light image of the page with a raking light image that shows the topography of the page, in varying amounts of 10% increments. The raking light image is the difference of the two infrared (940 nm) raking images, divided by the regular reflectance infrared (940 nm) image.

Aspects of manuscript enhanced: Folds, impressions, holes

Lead Scientist: Knox

flipbook

Original file name suffix: flipbook

Processing description: GIF animations or PowerPoint presentations of different sequences of pages, showing the color images side-by-side with the corresponding infrared difference raking light images. Two pages are shown on each slide, the recto image of a page together with the verso image of the previous page, as if the pages were open on the table and being flipped one page at a time.

Aspects of manuscript enhanced: folds, impressions, torn pages, holes, page discolor, the big stain, blotting and bleed through, brown stains, red stains

Lead Scientist: Knox

overlaid

Original file name suffix: overlaid

Processing description: PowerPoint presentations containing each color image of the diary. A page is followed directly by the aligned image of the other side of that page. By flipping back and forth between two slides, the presentations enable review of stain and image smear alignment between the two sides of a single leaf.

Aspects of manuscript enhanced: folds, page discolor, the big stain, blotting and bleed through, brown stains, red stains, miscellaneous singular stains

Lead Scientist: Knox

[various]

Original file name suffix: recto_color, recto_raking, recto_raking-color, verso_color, verso_raking, verso_raking-color

Processing description: GIF animations of pages liv_000205_0019-0036, recto only or verso only. All pages have been aligned to the holes in the pages. There are three types of files: those that show the natural light color images alone, those that show the infrared difference raking light images alone, and those that show the two images (color and raking) side-by-side.

Aspects of manuscript enhanced: impressions, torn pages, holes, the big stain

Lead Scientist: Knox

 

Notes on a Few Unusual Imaging Cases    Top

liv_000200_0006_PCA_pseudo_(liv_000205_0034_stats)

The original version of this image differed considerably from the other processed images of this type. The gray values of the image were therefore rescaled. In other words, the initial rendering of the brightest and darkest pixels for the image relied on statistical metrics that set "white" at the 98th percentile and "black" at the 2nd percentile of the numerical values of the pixels over the entire scene. In creating the rescaled version (the one used in this edition), therefore, we relied on the same calculations, but as applied over pixels only on the actual page of text, where the range of brightness values of pixels is smaller.

liv_000202_0004

Unfortunately, the original spectral imaging of this page failed to produced one of the required raw spectral images (535nm, i.e., the fifth band). As a result, during the present project we recreated this band by approximating it from the other available bands and, in turn, used this “synthetic” band in order to produce the other processed spectral images of this page.

liv_000202_0004_color

Due to a missing spectral band (see previous entry), the original version of this image differed considerably from the other processed images of this type. We thus modified the original image in Abode Photoshop CC 2015.5 by using Auto Tone and adjustments to the Brightness/Contrast, Hue/Saturation, and Color Balance in order to produce the version of the image used in this critical edition.

liv_000204_0001 and liv_000204_0002

The leaf that constitutes liv_000204 is unusually large. During the original imaging, the project team divided the leaf into quadrants and photographed each individually. We, therefore, turned Photoshop’s Photomerge feature to create the images available in the present edition.

liv_000204_0001_PCA_pseudo_(liv_000205_0034_stats)

Photomerge (see previous entry) produced unsatisfactory results in rendering the background of liv_000204_0001_PCA_pseudo_(liv_000205_0034_stats). The PCA pseudocolor images were thus rerendered for the present critical edition using a different scaling (linear 2% on a smaller section instead of over the full image) prior to stitching.

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