3.131 Upscale Image Resolution

Updated on Feb 10, 2025

In this article, you will learn

which requirements must be met for this Fixup and
how you can apply this Fixup.

1. Introduction

The Fixup Upscale Image Resolution is available in the Workflow. The purpose of this Fixup is to upscale the resolution of color, grayscale, and black-and-white images to a specified target resolution.

2. General

The Fixup Upscale Image Resolution can be used to upscale the resolution of images and thus reduce the sawtooth effect at the sharp edges of individual objects.

The Fixup can be found in the Data Preparation tab of an Article, Job, or Production Job by:

entering the name of the Fixup in the Filter area,
activating the Image option in the Category area,
activating the Compress and Downsample options in the Process area,
activating the CMYK, RGB, Grayscale, Black & White, and Image options in the Search area.

3. Description

This Fixup can be used to upscale color, grayscale, and black-and-white images, thereby increasing the resolution of the images according to the selected recalculation method. Choose how low the resolution of the respective images should be in order for them to be scaled up at all, as well as which compression algorithm should be used to compress the image.

3.1. Requirements and Functionality

In order for the function to do what it promises, the following requirements must be met:

The PDF file contains color, grayscale, and/or black and white images.
The PDF file contains images with a resolution lower than the resolution entered in the option For Resolution less than [4] | [8].

Figure 1: The dialog of the Fixup Upscale Image Resolution

Choose from the following options for upscaling the image resolution:

Templates [1] – settings selected in the dialog can be saved as a template and thus applied to other Articles or Print Items and used in the Fixup operation.

Color and Grayscale Images

Resample [2] – select the method for resampling here. The following options are available:
- Bicubic – Bicubic resampling calculates the average of the pixels that should be added. When calculating the average, the value around the color value of the surrounding pixels is included. When upscaling the resolution, this method leads to smoother tonal gradations.
- Average resampling – the average resampling also calculates the average value of the pixel. The color value of the surrounding pixels is not taken into account when determining the average value.
- Lanczos – is a complex type of resampling that, depending on the Print Item, usually leads to better results than those obtained with bicubic resampling.
- BlackmanSinc – is a complex type of resampling that, depending on the Print Item, leads to better results than those obtained with Bicubic downsampling.
- No downsampling – no downsampling of the image resolution is performed.
- Variable Content [10] – select the desired placeholder database field or user-defined field from which the value for selecting the recalculation method should be retrieved. The following values must be found in the selected field in order for the selection to be generated:
  - BicDownsampling
  - AvgDownsampling
  - LanczosDownsampling
  - BlackmanSincDownsampling
  - Off
Recalculate to [3] – enter the desired resolution in dpi for the grayscale or color image after upscaling. For Variable Content [11], select the desired placeholder – database field or custom field from which the value for the target resolution should be retrieved.
For resolutions smaller than [3] – enter the minimum resolution in dpi for images that should be resized. For Variable Content [12], select the desired placeholder – database field or user-defined field from which the value for the minimum resolution of the image to be resized should be retrieved.
Compression [5] – use the drop-down menu to select the compression method to be applied to the upsampled images. The following options are available:
- Unchanged – the existing compression method of the image is reused.
- Lossy (JPEG) – the upsampled images are compressed using the JPEG algorithm.
- Lossless (ZIP) – the upsampled images are compressed lossless using the ZIP algorithm.
- Variable Content [13] – select the desired placeholder – database field or custom field – from which the value for selecting the compression method should be retrieved. The following values must be found in the selected field for the selection to be generated:
  - RetainExisting
  - JPEG
  - ZIP

Figure 2: Left: Values found in the selected field for the Resample option; Right: Values found in the selected field for the Compression option

Monochrome Images

Resample [6] – select the resampling method here. The following options are available:
- Bicubic – during Bicubic resampling, the mean value of the added pixel is calculated. When calculating the mean value, the value is included with the color value of the surrounding pixels. If the mean value is over 50%, a white pixel is generated; if it is below, a black pixel is generated.
- Average resampling – with average resampling, the average value of the pixel is also calculated. In this case, the color value of the surrounding pixels is not taken into account when determining the average value. If the average value is above 50%, a white pixel is generated; if it is below, a black pixel is generated.
- Lanczos – a complex type of resampling that, depending on the Print Item, usually leads to better results than Bicubic resampling.
- BlackmanSinc – a complex type of resampling that, depending on the Print Item, usually leads to better results than Bicubic resampling.
- No Downsampling – no resampling of the image resolution is performed.
- Variable Content [14] – select the desired placeholder – database field or custom field – from which the value for selecting the resampling type should be retrieved. The following values must be found in the selected field to generate the selection:
  - AvgDownsampling
  - BicDownsampling
  - LanczosDownsampling
  - BlackmanSincDownsampling
  - Off
Recalculate to [7] – enter the desired resolution in dpi for the black and white image after upsampling. For Variable Content [15], select the desired placeholder database field or user-defined field from which the value for the resolution of the target file should be retrieved.
For resolution less than [8] – enter the image resolution in dpi that should be affected by the extrapolation. For Variable Content [16], select the desired placeholder – database field or user-defined field – from which the value for the target resolution should be retrieved.
Compression [9] – use the drop-down menu to select the compression method to be applied to the upscaled images. The following options are available:
- Unchanged – the existing compression method of the image is reused.
- CCITT Group 4 – CCITT Group 4 is a lossless symmetrical and non-adaptive compression method.
- JBIG – JBIG encoding is a lossy and lossless compression method that has been an integral part of PDF since PDF 1.4.
- Variable Content [17] – select the desired placeholder – database field or custom field – from which the value for selecting the compression type should be retrieved. The following values must be found in the selected field for the selection to be generated:
- RetainExisting
- CCITTG4
- JBIG2

Figure 3: Left: Values found in the selected field for the resampling option; Right: Values found in the selected field for the compression option

3.2. Before/After

To experiment with this function, please refer to the example file Sample_Upsampling.pdf. The image has a size of 250.12 x 166.51 mm and a resolution of 72 dpi.

After the Fixup was applied and the file Sample_Upsampling_End.pdf is created. The image was upsampled to 300 dpi using the values from Figure 1.

Figure 4: Left: original file with an image resolution of 72 dpi; Right: revised file with an image resolution of 300 dpi