Digital Image Quality Guidelines by mr8ball3

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									                      Digital Image Quality Guidelines
                                   For the 2003-04 School Year



Introduction
Taylor Publishing has long been a supporter of the Professional School Photographers
Association (PSPA) and the efforts of this group to establish a standard for photographers, labs
and publishers to follow in the production of products and services provided to the customers of
both the school picture industry as well as the yearbook publishing industry, who are one and the
same. A standard for image formatting was first published by the PSPA in 1996 as the Digital
Image Format Guideline, and was recently updated to include information regarding color image
file formats. The Digital Image Format Guideline is freely downloadable from the PSPA website
and is available at http://pspa.pmai.org/pdf/PSPA_Guidelines.pdf.
The PSPA Digital Image Format Guideline, however, is designed only to address formatting of
the CD, and the files that are contained on the CD. It does not seek to provide guidance, nor a
standard, for the quality of the images on that CD. In the absence of a definitive quality standard
that photographers, labs and publishers can all agree upon, this document sets in place a
standard for image quality. Our hope is that this guideline could form the basis for a more formal
standard set forth by the PSPA in the near future.


Benefits
The primary benefit of adherence to this guideline is consistency and higher fidelity reproduction
of the original sitting, through the supplier-chain from photographer to publisher. Furthermore, all
suppliers in this supplier-chain benefit from adherence to this standard, as end customers (school
administrators, students and parents), who are the ultimate beneficiary, expect us to work
together and deliver consistently high quality results.


Our Goal
Taylor Publishing provides these guidelines to participating labs and/or photographers with the
goal of delighting our end customer with a quality publication, while reproducing as faithfully as
possible the exact image the photographer captured in the originating photographic medium.
Taylor Publishing does not perform any image processing on supplied digital images other than to
convert the supplied image from the source color space to the required printing color space of
CMYK. This is done in all facilities by utilizing an industry standard ICC-based color management
system and a Taylor specific CMYK ICC profile which represents our printing environment. If you
are interested, you may obtain the “TPC_Std_CMYK.icc” profile via our EZ Pix Support (see
Technical Support below).
Taylor Publishing does perform a Quality Assurance process on every CD received in each
production facility. The CD is checked for conformance to the PSPA Guidelines and to these
Quality Guidelines. If a CD does not pass the QA process, the photographer or lab will be
contacted, given specific information as to where the deficiency lies, and requested to submit a
replacement CD. We recommend that you send in a test CD for evaluation prior to sending a CD



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to one of our production facilities for inclusion in a publication. Please see the instructions at the
end of this document on where to send test CDs.


Definitions and Terms
This document will use the term Digital Image CD or just CD in reference to the PSPA formatted
CD, and the term Image Producer in reference to any organization that creates a Digital Image
CD. An Image Producer may be any photography organization that produces their own Digital
Image CDs, or any lab that produces Digital Image CDs for photographers.


Quality Guidelines
     1.   Submission of Grayscale Images (for B&W reproduction):
               a.   All images should be free of visually noticeable compression or interpolation
                    artifacts, sometimes referred to as aliasing.
               b.   All images should have a good, but not excessive, sharpness level. Noticeable
                    white-lines/black-lines at image transitions are characteristic of sharpness levels
                    set too high.
               c.   Perhaps the most important visual qualities of any image are Brightness and
                    Contrast. Brightness refers to the viewer’s perceived ability to detect or see a
                    wide range of tones throughout the image, particularly through the predominant
                    middle tones. Contrast refers to the viewer’s perceived ability to differentiate
                    between those tones.
                          i. The recommended method for statistically determining Brightness is the
                             Luminosity Mean. The recommended range for Luminosity Mean is 88
                             to 168.
                         ii. The recommended method for statistically determining contrast is to use
                             Luminosity Standard Deviation (StdDev). The recommended range for
                             StdDev is 50 to 130.
                         iii. In addition, the recommended range for minimum pixel levels is 0 to 15.
                              And the recommended range for maximum pixel levels is 240 to 255.
                              Image Producers should be careful to not allow too many pixels to reach
                              level 0 (pure black) or level 255 (pure white). We recommend not more
                              than 2% of all pixels to be level 255 and not more than 5% of all pixels to
                              be level 0.
               d.   For those creating grayscale images by converting from original RGB images,
                    the recommended RGB-to-Grayscale conversion parameters are:
                          i. Gray = 40% R + 50% G + 10%
                         ii. Apply a general curve to “open image” where (input = output): 0 = 0; 25 =
                             13; 50 = 38; 75 = 74; 100 = 97
               e.   The Image Producer should perform a final visual inspection of grayscale images
                    on a computer display with the “Dot Gain 20%” ICC profile as the Gray working
                    profile. The Image Producer is recommended to save and supply the final
                    Grayscale images with the Dot Gain 20% ICC profile embedded.


     2.   Submission of RGB or CMYK Images (for color reproduction only):
               a.   Items (a) (b) and (c) from Section 1 above apply to RGB or CMYK images also.



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               b.   In addition to the above, RGB or CMYK images should be free of any visually
                    noticeable color cast. This is most evident in neutral and near-neutral tones. We
                    recommend that all images be processed for cast correction by the Image
                    Producer where intended neutral tones (i.e. gray backdrops) are corrected to be
                    closer to the intended neutral tone.
               c.   If supplying RGB images, the Image Producer should perform a final visual
                    inspection of RGB images on a computer display with the “sRGB” ICC profile as
                    the RGB working profile. The Image Producer is recommended to save and
                    supply the final RGB images with the sRGB ICC profile embedded.
               d.   If supplying CMYK images, the Image Producer should perform a final visual
                    inspection of CMYK images on a computer display with the
                    “TPC_Std_CMYK.icc” profile as the CMYK working profile. The Image Producer
                    is recommended to save and supply the final CMYK images with this Taylor ICC
                    profile embedded.
     3.   It is recommended that Image Producers maintain consistent head sizes from photo to
          photo. Remember, all of these images will be viewed side-by -side, in a panel, and comes
          off looking very bad when they are bouncing around. We recommend that you size the
          heads by leaving a small amount of space between the top of the head and the top edge
          of the image, and by placing the chin of the subject about the same distance below the
          mid point of the image.
     4.   It is recommended that Image Producers maintain consistent lighting and exposure
          throughout all images; or, alternatively, post-process images to correct for photographic
          lighting/exposure inconsistencies prior to submitting images to Taylor Publishing. Neither
          ICC profiles, nor ICC-compliant workflows, can correct for lighting or exposure
          inconsistency within a series of images. On the contrary, ICC profiles characterize a
          particular device or workflow, and compensate for consistent and repeatable error or
          deviation from a standard or reference.
     5.   It is recommended that Im age Producers photograph subjects against medium to light,
          neutral backdrops. Bright and saturated color backdrops or the use of gel lights can
          cause a color cast on the subject. Dark backdrops, even dark neutral backdrops, create a
          lack of separation (or depth) between the subject and the backdrop, particularly when the
          subject has darker skin tones.


Technical Support
Taylor Publishing provides technical support for those Image Producers who wish to supply digital
image CDs for evaluation and feedback, and to answer any general technical questions about
Taylor’s EZ Pix program. You may contact us toll free at 800-944-7150, or email us at
ezpix_support@taylorpub.com for more information. To send us a test CD for evaluation, please
have it shipped to:

                    EZ Pix Support
                    Taylor Publishing
                    1550 West Mockingbird Lane
                    Dallas, TX 75235




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