Pdf Configuration
The parameters pageSize, pageFit, dpi and resamplingMethod interact in a complex way when adding bitmap images (JPEG, PNG, or raw) to the PDF. There are three cases to consider:
pageSizeisCUSTOM: in this casedpiis used as the conversion ratio to calculate both the physical page and image sizes in inches from the bitmap dimensions.resamplingMethodis ignored.pageSizeis notCUSTOMANDpageFitisNONE: in this casedpiis used as the conversion ratio to calculate only the physical image size in inches from the bitmap dimensions. The image is centered onto the page.resamplingMethodis ignored.pageSizeis notCUSTOMANDpageFitis notNONE: in this case the page has a pre-determined physical size and we want to stretch the image to fit the page in one of the ways described bypageFit. The image DPI is automatically calculated for each image from the given physical page size, page fit setting and image dimensions. There are two sub-cases to consider: a.resamplingMethodis NONE OR the calculated DPI is less than or equal todpi: in this case the image is added to the PDF without resampling, which means that the image rectangle is simply rescaled to fit into the page as specified bypageFitandpageSize. b.resamplingMethodis not NONE AND the calculated DPI is greater thandpi: in this case the bitmap of the image is resampled to matchdpiusing the selected method before adding it to the PDF. This will result in a bitmap that is smaller than the original image and hence, the resulting PDF will be smaller in size.
Constructors
Properties
Attributes.
Filter to apply to the input image when adding pages with binarization.
The dpi parameter has two different meanings depending on the value of pageSize and pageFit. If pageSize is CUSTOM or pageFit is NONE, then dpi is the conversion ratio used to convert from units of pixels to physical inches when adding bitmap images (JPEG, PNG, or raw) to the PDF. Otherwise, if resamplingMethod is not NONE, then the image is downscaled if necessary (if the image after being fit to the page has a higher calculated DPI than dpi) to match dpi before adding it to the PDF. Otherwise, the setting is ignored and the calculated image DPI is used instead.
JPEG quality for images. Applies if an image is added as a cv::Mat and therefore needs to be encoded. Also applies if resamplingMethod not NONE and the image being added needs to be downscaled. Otherwise, when adding JPEG files to the PDF, the files are copied directly into the PDF and not re-encoded, which is many times faster and also preserves the quality of the original.
Page direction.
Resampling method.