CN103136171B - E-book making method based on shock wave flash (SWF) - Google Patents

Abstract

The invention discloses a method for making an electronic book based on SWF, and relates to the technical field of information data processing. This method first classifies the content of each page of the PDF document to be processed, then sets the corresponding conversion parameters for each page type, and finally converts the PDF file into a SWF file according to the set conversion parameters, and adds The upper data header forms the final electronic book. Better results are obtained due to the adoption of different conversion strategies for different content types when converting to SWF. In addition, after the conversion is completed, unsatisfactory pages can be processed separately through manual inspection to further improve the overall effect. The method described in the invention ensures high document definition without reducing the color bit depth and achieves a smaller size at the same time.

Description

A Method of Making Electronic Books Based on SWF

technical field

The invention relates to the technical field of information digital processing, in particular to a method for making high-fidelity electronic books based on SWF suitable for network transmission, especially suitable for occasions requiring high visual effects and volume.

Background technique

E-books are widely used, and the acquisition of e-books can be copied to the local through mobile storage media, such as U disk, mobile hard disk, CD, etc. for copying. But in many cases, e-books are downloaded through the network. In a distributed system, books may need to be transmitted multiple times between multiple servers before being delivered to the final client. Therefore, how to reduce the size of electronic books is extremely important.

Under the existing technology, the volume of e-books is reduced, in many cases at the cost of greatly reducing their clarity and color. But in many occasions, we don't want to reduce its clarity, such as electronic textbooks for primary and middle school students. Based on the characteristics of primary and middle school students, we hope to maintain the high definition of the textbooks without significantly losing the color of the books. At present, the electronic books issued by various publishing houses, especially the electronic teaching materials (textbooks) for primary and secondary schools, are basically in PDF format, which is characterized by bright colors, clear characters, and large volume. For a system that needs to transmit electronic books through the network, the above-mentioned bulky electronics is undoubtedly inappropriate.

Adobe's SWF (shock wave flash) file uses vectorization technology, which can significantly reduce the volume of e-books under certain conditions, so converting PDF to SWF is a better solution. Currently, there are many softwares on the market that support converting PDF to SWF, such as gpdf2swf, PDFZilla, FlashPaper2, macromedia flashpaper, etc., but these softwares do not support program calls and can only be operated manually. Thus, it is often difficult to integrate these conversion software into one's own e-book authoring software. To use PDF to convert SWF in the book production system, there are two options: 1) Since both PDF and SWF files are open files, there are also many open source analysis libraries, such as XPdfLib, etc., which can be used to analyze PDF files by yourself , and produced in SWF file format. 2) Call some components or background programs, such as PDF2SWF and so on. Either way, it is necessary to set reasonable conversion parameters for different PDF contents in order to obtain the best results. In addition, most of the currently existing conversion tools use a unified strategy for conversion, and the pertinence is poor.

In current electronic documents, there are usually several forms of expression for text: 1) using vector fonts; 2) using dot matrix fonts; 3) converting characters into bitmap displays.

Among them, the vector font library is also called font vector, vector font (Vector font), and both are called font vector in this article. Font vectors are the most widely used form today. Each glyph is described by a mathematical curve, which contains the key points on the glyph boundary, the derivative information of the connection, etc. The rendering engine of the font reads these mathematical vectors and then performs certain mathematical operations for rendering. Compared with this type of font, the advantage is that the actual size of the font can be scaled arbitrarily without deformation or discoloration. Compared with dot-matrix fonts, font vectors have the advantages of occupying less data and not being deformed when zoomed.

Dot-matrix fonts divide each character into 16×16 or 24×24 dots, and then use the virtual reality of each dot to represent the outline of the character. The advantage is that the display speed is fast, unlike vector fonts that need to be calculated; the biggest disadvantage is that it cannot be enlarged, and once enlarged, you will find jagged edges of the text. Nowadays, this kind of dot matrix font is mainly used as an "auxiliary" part and is rarely used.

Converting characters to bitmap display has nothing to do with characters. For example, e-books generated by scanning paper books and taking photos with digital cameras into images belong to this type.

In addition, in some specific occasions, such as some artistic words used in advertisements, they are often designed in the form of vector graphics, which are not characters in essence, but an image.

In current e-books, images usually have 2 representations: 1) using vector graphics; 2) using bitmaps.

Vector diagrams are also called Polygon diagrams, vector diagrams, and drawing images, all of which are referred to as Polygon diagrams or Polygons in this article. Polygon graphs represent images in computer graphics with geometric primitives such as points, lines, or polygons based on mathematical equations. The advantage of vector graphics is that the file takes up less space and will not be distorted no matter whether it is enlarged, reduced or rotated; the disadvantage is that it is difficult to express realistic image effects with rich color levels, and the drawing efficiency is not as high as that of bitmap images.

Bitmaps are also called bitmaps, raster images, and pixel images. Simply put, they are images whose smallest unit is composed of pixels, and will be distorted when zoomed. The smallest unit that constitutes a bitmap is a pixel, and the bitmap realizes its display effect by the arrangement of the pixel array. Its advantage is that it can produce colorful, complex and changeable images; its disadvantage is that it is bulky.

From the above discussion, it can be seen that from the perspective of reducing the volume of electrons, it can be considered to represent the text in the e-book with a vector font (font vector); the image is better represented in the form of a vector diagram. But in reality, the final volume is also related to the content. For example, vector graphics are suitable for expressing simple graphics, so for simple graphics, vector graphics data is much smaller than bitmap data. But if the original image is a bitmap, and the bitmap contains complex shapes and many colors, the converted vector graphics will be larger than the original bitmap! Therefore, it is not appropriate to vectorize all e-books containing complex images. For complex bitmaps, converting them to compressed formats such as jpeg can often obtain smaller volumes. If necessary, convert some complex bitmaps into vectors, and then manually smooth the vectors with editing tools such as Flush to obtain a better balance of color, effect, and volume; but for some complex content, forced smoothing Afterwards, there will be a large gap with the original image, which will lose the aesthetics. Therefore, the volume reduction of e-books is a complicated process, which needs to be designed according to different situations, and if necessary, it needs to be assisted manually to obtain the best results.

Contents of the invention

Aiming at the defects existing in the prior art, the purpose of the present invention is to provide a method for making electronic books based on SWF. For different PDF contents, different conversion settings are adopted when converting to SWF, so that the converted files are guaranteed to be relatively stable. High definition, while achieving a smaller size for better conversion effects.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A method for making an electronic book based on SWF, comprising the following steps:

(1) Open the PDF file to be processed, analyze the content of each page in the PDF file and classify the content of each page; divide the content of each page in the PDF file into 5 types: text-based, image-based Auxiliary type, the text converted into an image is the main type, the image is the auxiliary type, the image is the main type, the text is the main type, the image is the background type, and a comprehensive graphic and text mixed type;

(2) According to the type of content of each page of the PDF file, the parameters when converting PDF to SWF are respectively set;

(3) Convert the PDF file into a SWF file according to the conversion parameters set;

(4) Compressing the converted SWF file and adding a file header to form the final electronic book.

Further, a kind of electronic book production method based on SWF as above, in step (2), the parameter setting when PDF is converted into SWF is as follows:

When the content in the PDF file is text-based and images are auxiliary types, the text remains as a font vector, and the image is converted to a polygon image;

When the content in the PDF file is text converted to images as the main type and images as the auxiliary type, the polygon image remains as a polygon image, and other images are converted to Jpeg format;

When the content in the PDF file is image-based, the polygon image remains as a polygon image, and other images are converted to Jpeg format;

When the content in the PDF file is mainly text and the image is the background type, convert the image to Jpeg format, and keep the text as a font vector;

When the content in the PDF file is a comprehensive image-text type, the polygon image remains as a polygon image, and other images are converted to Jpeg format.

Further, a kind of SWF-based e-book making method as mentioned above, in step (2), when setting parameters, when the content in the PDF file is converted into the text of the image as the main type, and the image as the auxiliary type, convert to The image in the Jpeg format is set as medium definition; the medium definition means that the quality parameter range of Jpeg is 70-80.

Further, a kind of SWF-based e-book making method as described above, in step (2), when setting parameters, when the content in the PDF file is the main type of image, the image converted to Jpeg format is set as high-definition The high definition means that the Jpeg quality parameter is 95-100.

Further, a kind of electronic book production method based on SWF as mentioned above, in step (2), when setting parameters, when the content in the PDF file is mainly text, and when the image is the background type, it is converted into an image in Jpeg format Set to low definition; the low definition means that the Jpeg quality parameter is 60-65.

Further, a kind of SWF-based e-book production method as described above, in step (2), when setting parameters, when the content in the PDF file is a comprehensive graphic and text mixed type, it is converted to an image setting in Jpeg format for medium sharpness.

Further, in the method for making an electronic book based on SWF as described above, in step (3), after the PDF file is converted into a SWF file, manual inspection is performed on the converted file, and pages that do not meet the requirements are processed separately.

Still further, in the aforementioned SWF-based e-book production method, in step (4), the converted file is compressed using the Zip algorithm.

Furthermore, in the above-mentioned method for making an electronic book based on SWF, the compressed file is encrypted using a key.

The effect of the present invention is that the method of the present invention firstly distinguishes different contents of PDF, and adopts different conversion settings when converting to SWF in combination with different contents, so as to obtain the best effect. In addition, the electronic book production tool also uses compression techniques such as Zip to further reduce the size of the book. Encrypt with a key to obtain better confidentiality. This file ensures high document clarity, does not reduce the color bit depth, and at the same time achieves a small size, and is especially suitable for occasions that require high visual effects and volume.

Description of drawings

Fig. 1 is a kind of flowchart of the electronic book production method based on SWF of the present invention;

Fig. 2 is the one-page PDF file that text is main content, image is background type in the specific embodiment;

Figure 3 is a partial view of the SWF file generated after the file in Figure 2 is converted using default parameters;

Fig. 4 is the partial figure of the SWF file that generates after the file among Fig. 2 is converted by the method for the present invention;

FIG. 5 is a partially enlarged view of FIG. 4 .

detailed description

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 has shown the flow chart of a kind of electronic book making method based on SWF of the present invention, find out that this method mainly comprises the following steps from the figure:

Step S11: classify the content of each page of the PDF file to be processed;

Open the PDF file to be processed, analyze the content of each page in the PDF file and classify the content of each page; divide the content of each page in the PDF file into 5 types: text (embedded/external link) is The main + image is the auxiliary type, the text converted into an image is the main + image is the auxiliary type, the image is the main type, the text is the main + image is the background type, and a comprehensive graphic and text mixed type.

Step S12: setting conversion parameters according to the type of PDF content of each page;

After the content of each page of the PDF file is classified in step S11, the parameters for converting PDF to SWF are respectively set according to the type of content of each page of the PDF file. The specific setting method is as follows:

1) Text (embedded/external link) is the main type, and images are the auxiliary type;

When setting parameters, the text is kept as a font vector, and the image is converted into a polygon map.

2) The text has been converted to an image-based and image-assisted type;

When the parameters are set, the polygon image remains the polygon image, and other images are converted to Jpeg format, and the Jpeg format image is set to medium definition.

3) Images are the main content and less text;

When setting the parameters, the polygon image remains the polygon image, the image is converted to Jpeg format, and the image in Jpeg format is set to high-definition.

4) Types in which text is the main content and images are the background;

When setting parameters, the image is converted to Jpeg format and set to low definition, and the text remains font vector.

5) Comprehensive graphics and text mixed type.

When setting the parameters, the Polygon image keeps the polygon image, the image is converted to Jpeg format, and the Jpeg format image is set to medium resolution.

In this specific embodiment, 5 kinds are relatively common types. Of course, for the classification of PDF document content, the user can perform different classifications according to actual needs. Among the five common types, the medium definition, high definition and low definition set refer to the difference in image quality parameters. The image in Jpeg format is a lossy compressed image, and its compression rate is usually represented by a quality parameter (referred to as quality), also known as Q factor or compression factor. The quality factor has a value from 1 to 100. The smaller the value, the higher the compression, that is, the greater the loss of pixel quality. Common Jpeg images have a quality of 60-80%. In the process of converting to Jpeg, you can set the quality of jpeg according to different situations. For example, if the image is only an unimportant background image, you can set its quality to a lower quality; Set its quality to a higher quality, etc. In this specific embodiment, medium definition means that the Jpeg quality range is 70-80, high definition means that the Jpeg quality range is 95-100, and low-resolution Jpeg quality range is 60-65.

Step S13: converting the PDF file into a SWF file according to the set conversion parameters;

Convert the PDF file into a SWF file according to different conversion parameters set according to different content types in step S12. Converting PDF to SWF belongs to the existing technology, and users can choose the required conversion software according to their needs. To convert PDF files to SWF vectorization is to convert PDF files into SWF files, which can be carried out by using gpdf2swf or other existing software; in addition, since the PDF and SWF file formats are open, you can also write programs to read, Write conversion processing.

If necessary, manual inspection is performed after the conversion is completed, and unsatisfactory pages can be processed separately. Using this method of combining program interpretation and manual inspection can get better results.

The following table shows the different parameter settings when using the method of the present invention in practical application for SWF conversion of different types of PDF content on each page, and the file size comparison before and after conversion. As can be seen from the table, after adopting the method of the present invention to convert, the size of the converted file is significantly reduced compared with the original document, and for the latter three types, the method of the present invention is compared to the default parameter conversion method, its effect is also very obvious, and the file size is also obviously reduced.

Table 1

Step S14: Adding a data header to the SWF file to form a final electronic book.

Compress the converted SWF file and add a file header to form the final e-book. In practical applications, after compressing the converted SWF, such as using the Zip algorithm, you can use a key to encrypt the compressed data to obtain better confidentiality, and then add a data header to the file, form the final e-book.

When the above-mentioned method of the present invention is used to make electronic books, the problem of poor pertinence when the PDF file is converted into a SWF file in the prior art is overcome, especially the serious problem of document clarity, size and color conflicts, generally When one of the characteristics is highlighted, it is often at the expense of other characteristics. The method of the present invention sets different conversion parameters for different content types to ensure higher document clarity and color fidelity. conditions while maintaining a small file size.

In order to better understand the technical solution of the present invention, the method of the present invention will be further described in detail below in conjunction with specific embodiments.

Example

In this embodiment, the content of the fourth type of PDF file (text is the main content, and the image is the background type) is taken as an example for illustration.

As shown in Figure 2, the original PDF document is very clear, and its size is 683k. If the document on this page is converted using the default configuration, the part of the conversion result is shown in Figure 3. It can be seen that the converted image is also very clear, but the size is relatively large, 121k, which is required to reduce the volume size. , the result is not ideal.

The PDF content is converted using the method described in the present invention below.

First judge with the method described in the present invention, know this PDF content, its text is main content, and image part is less, therefore adopt " image is converted into Jpeg form, and be set to very low definition, text keeps font vector " setting scheme. After setting according to the above parameters, the existing technology is used to convert the PDF file into a SWF file, and the converted result is partially shown in Figure 4. It can be seen that in the converted SWF file, the image part is blurred, but the text part is very clear, and the converted file size is 45K. Obviously, in this case, the reader does not care about the auxiliary image part, and it is acceptable for the image part to appear blurry. But the text part is very important and is the focus of readers' reading. At this time, it should be ensured that the font is represented by vectors to obtain high-definition text, and the size result is also ideal.

Figure 5 is a partial zoom-in of Figure 4, and it can be seen that the image part has become more blurred. But because it is not important from the perspective of content, we can accept this kind of blurring; and the text part of the main body, because it is converted into a vector, still maintains a high definition when it is enlarged a lot.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (8)

1. A method for making electronic books based on SWF, comprising the following steps: (1) Open the PDF file to be processed, analyze the content of each page in the PDF file and classify the content of each page; divide the content of each page in the PDF file into 5 types: text-based, image-based Auxiliary type, the text converted into an image is the main type, the image is the auxiliary type, the image is the main type, the text is the main type, the image is the background type, and a comprehensive graphic and text mixed type; (2) According to the type of content of each page of the PDF file, set the parameters when converting PDF to SWF respectively; the parameters when converting PDF to SWF are set as follows: When the content in the PDF file is text-based and images are auxiliary types, the text remains as a font vector, and the image is converted to a polygon image; When the content in the PDF file is text converted to images as the main type and images as the auxiliary type, the polygon image remains as a polygon image, and other images are converted to Jpeg format; When the content in the PDF file is image-based, the polygon image remains as a polygon image, and other images are converted to Jpeg format; When the content in the PDF file is mainly text and the image is the background type, convert the image to Jpeg format, and keep the text as a font vector; When the content in the PDF file is a comprehensive image-text type, the polygon image remains as a polygon image, and other images are converted to Jpeg format; (3) Convert the PDF file into a SWF file according to the conversion parameters set; (4) Compressing the converted SWF file and adding a file header to form the final electronic book. 2. a kind of method for making electronic books based on SWF as claimed in claim 1, it is characterized in that: in step (2), when setting parameters, when the content in the PDF file is converted into the text of image mainly, image When it is an auxiliary type, the image converted to Jpeg format is set to medium definition; the medium definition means that the quality parameter range of Jpeg is 70-80. 3. a kind of method for making electronic books based on SWF as claimed in claim 1, it is characterized in that: in step (2), when setting parameter, when the content in PDF file is that image is main type, change to Jpeg The format of the image is set to be high-definition; the high-definition means that the Jpeg quality parameter is 95-100. 4. a kind of method for making electronic books based on SWF as claimed in claim 1, it is characterized in that: in step (2), when setting parameters, when the content in the PDF file is mainly text, when image is background type , the image converted to Jpeg format is set to low definition; the low definition refers to the Jpeg quality parameter being 60-65. 5. a kind of method for making electronic books based on SWF as claimed in claim 1, is characterized in that: in step (2), when setting parameter, when the content in the PDF file is the integrated graphic and text mixed arrangement type, The image converted to the Jpeg format is set to medium definition; the medium definition means that the quality parameter range of Jpeg is 70-80. 6. a kind of method for making electronic books based on SWF as claimed in claim 1, it is characterized in that: in step (3), after PDF file is converted into SWF file, manual inspection is carried out to the file after conversion, does not conform to Required pages are processed separately. 7. A kind of SWF-based electronic book making method as claimed in claim 1, is characterized in that: in step (4), adopt Zip algorithm to compress the converted file. 8. A method for making an electronic book based on SWF as claimed in claim 7, characterized in that: the compressed file is encrypted using a key.