Automatic Image Enhancement (AIE)

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The AIE algorithms resulted from the need to improve high resolution images that are downsized to the product DPI, emphasizing camera chip artifacts (grain, noise, error pixels) and undesired color desaturation in the printed product. As of Publisher version 3.5, the product designer can overcome these side effects to a certain extent by turning on AIE in the Products.xml. AIE is very time consuming (up to 30 secs per image), so we recommend that you test your settings with all products and on all printers that you use.

You may not need AIE at all. An alternative is to display a button in the user interface, where the user can pick the photos himself, where he wants to apply this enhancement. See PRODUCTS.XML for a description of the AIE tags.

Aspects of AIE

AIE mainly does histogram corrections, i.e. takes care of contrast and color range problems resulting from bad lighting situations (high ISO) or overpixeled camera chips. It may improve pixelation (grain) and color problems (desaturation). If an image has grain in the highres version, then this unwanted artifact will be emphasized in the downsized or cropped (= zoomed) version, so we try to remove it beforehand. Similarly, if an image has a histogram problem (too much contrast, too little color saturation), then this will also worsen during downsizing.
The Lanczos3 antialias filter is used for internal downsizing, as it sharpens the image much better.
AIE applies to all products at once. Also, the histogram improvements are so conservative and equally good to all images, that we have chosen not to ask the user. Given a choice, he probably will not notice a difference on his screen or - even worse - doubt his choice later after receiving the printed product.
All AIE is done during rendering of the PDF pages, thus slowing down the process considerably. Therefore, AIE should only be switched on in the products.xml, if the printing result is noticeably better.
The HighRes warning dialog appears when adding a large image to the page, where pixelation may become a problem in extensive downsizing or cropping. It has a Don't show again checkbox, a custom text (can be translated and thus altered), and a More info link. An option in the products.xml defines the quality threshold, as of which the dialog will appear.

If turned on, AIE is performed shortly before the product is uploaded, i.e. when the PDF pages are generated. The user cannot interact with this, as the enhancements are so subtle and only affect the downsized images, that he would not be able to see the changes on his computer screen. In fact, AIE can be considered an automatic non-linear color profiling, which mainly affects those images that would have negative downsizing side effects.

From our test with different printers, we have come up with two good AIE value sets. We recommend set #1, but again, this is dependent on your own printing machine. Values range from 0..255, so low values imply a subtle effect.

Set #1: SmartFlash 20, SmartFix 60, NoiseReduction 150

Set #2: SmartFlash 20, AutoExposure 50, AutoColor 50, Saturation 20, NoiseReduction 150



Original image


Adobe ICC profile applied


AIE set #1 applied

Here’s the corresponding section of the Products.xml:


          <SmartFlash enabled="1">20</SmartFlash>

          <SmartFixColorHistoStretch enabled="1">60</SmartFixColorHistoStretch>

          <SmartFixSaturation enabled="1">60</SmartFixSaturation>

          <SmartFixShadowHighlights enabled="1">60</SmartFixShadowHighlights>

          <AutoExposure enabled="1">50</AutoExposure>

          <AutoColor enabled="1">50</AutoColor>

          <Gamma enabled="0">0</Gamma>

          <Saturation enabled="0">20</Saturation>

          <NoiseReduction enabled="1" threshold="600">150</NoiseReduction>




To reduce processing time, switch off NoiseReduction (~ 15 secs/image), which is applied to the original full sized images before they are downsized. NoiseReduction removes grain/noise and pixelation in the full sized image, thus solving downsizing alias effects, if problematic HighRes images are used in product. Since it may also reduce sharpness in intentional textures, this algorithm is only applied to images above the image quality threshold attribute. (see also High Resolution Warning).

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