Maintaining advance widths of existing characters that have been resolution enhanced

Claim 2

In a rendering system that processes characters having existing formatting associated with a pixel precision resolution and renders the characters at a sub-pixel precision resolution, a method for rendering the characters at the sub-pixel precision resolution while maintaining the layout of a document that includes the characters when the characters are rendered at the sub-pixel precision resolution, the method comprising: obtaining a document having a layout associated with pixel precision resolution, the document including characters having a particular font and a particular point size and having pixel precision advance widths and pixel precision black body widths associated with the pixel precision resolution; in preparation for displaying the document on a display device that is capable of displaying the characters with sub-pixel precision resolution, hinting the characters to pixel sub-component boundaries without changing the particular font or the particular point size, thereby: changing the pixel precision black body widths to resolution enhanced black body widths associated with the sub-pixel precision resolution; and changing the pixel precision advance widths to resolution enhanced advance widths associated with the sub-pixel precision resolution, at least some of the resolution enhanced advance widths being different from the corresponding pixel precision advance widths; replacing said at least some of the resolution enhanced advance widths with the corresponding pixel precision advance widths, thereby maintaining the layout of the document as the layout existed prior to the act of hinting; and displaying the document on the display device, wherein the displayed document includes the hinted characters and further has the layout as the layout existed prior to the act of hinting.

Claim 3

The method of claim 1 , further comprising, after the act of hinting, the act of adjusting the resolution enhanced black body width of each of a plurality of characters based on the resolution enhanced advance width of the character and the pixel precision advance width of the character.

Claim 4

The method of claim 2 , wherein the act of adjusting the resolution enhanced black body width of each of the plurality of characters is performed by scaling points defining an outline of the character by a ratio of the pixel precision advance width of the character to the resolution enhanced advance width of the character.

Claim 5

The method of claim 3 wherein each of the points defining the outline of the character arc scaled by scaling an X coordinate of the character.

Claim 6

The method of claim 2 , wherein the act of adjusting the resolution enhanced black body width of each of a plurality of characters is performed by multiplying the resolution enhanced black body width of the character by a correction factor defined by the pixel precision advance width of the character divided by the resolution enhanced advance width of the character, wherein limiting the correction factor is limited if the correction factor would otherwise be greater than a predetermined maximum limit.

Claim 7

The method of claim 5 wherein the predetermined maximum limit is approximately 1.2.

Claim 8

The method of claim 2 , wherein the act of adjusting the resolution enhanced black body width of each of the plurality of characters is performed by multiplying the resolution enhanced black body width of the character by a correction factor defined by the pixel precision advance width of the character divided by the resolution enhanced advance width of the character, wherein limiting the correction factor is limited if the correction factor would otherwise be less than a predetermined minimum limit.

Claim 9

The method of claim 7 wherein the predetermined minimum limit is approximately 0.8.

Claim 10

The method of claim 2 , further comprising, prior to the act of displaying the document, the act of moving the black body of a particular character to the left if the resolution enhanced black body width of the particular character is greater than the pixel precision black body width of the particular character.

Claim 11

The method of claim 9 , wherein the act of moving the black body of the particular character comprises the act of decreasing a left side bearing metric associated with the particular character.

Claim 12

The method of claim 10 , wherein the act of decreasing the left side bearing metric is performed by decreasing the left side bearing by one half of a difference between the pixel precision black body width of the particular character and the resolution enhanced black body width of the particular character.

Claim 13

The method of claim 2 , further comprising, prior to the act of displaying the document, the act of moving the black body of a particular character to the right if the resolution enhanced black body width of the particular character is less than the pixel precision black body width of the particular character.

Claim 16

The method of claim 13 , wherein the act of increasing the left side bearing metric is performed by increasing the left side bearing by one half of a difference between the pixel precision black body width of the particular character and the resolution enhanced black body width of the particular character.

Claim 17

In a rendering system that processes characters having existing formatting associated with a pixel precision resolution and renders the characters at a sub-pixel precision resolution, a method for rendering the characters at the sub-pixel precision resolution while maintaining the layout of a document that includes the characters when the characters are rendered at the sub-pixel precision resolution, the method comprising: obtaining a document having a layout associated with pixel precision resolution, the document including characters having a particular font and a particular point size and having pixel precision advance widths and pixel precision black body widths associated with the pixel precision resolution; in preparation for displaying the document on a display device that is capable of displaying the characters with sub-pixel precision resolution, hinting the characters to pixel sub-component boundaries without changing the particular font or the particular point size, thereby: changing the pixel precision black body widths to resolution enhanced black body widths associated with the sub-pixel precision resolution; and changing the pixel precision advance widths to resolution enhanced advance widths associated with the sub-pixel precision resolution; for each of a plurality of the characters in the document, performing the acts of: determining whether the character is a mono-stem character; replacing the advance width of the character with the pixel precision advance width of the character that existed prior to the act of hinting, thereby maintaining the layout of the document as the layout existed prior to the act of hinting; and adjusting the resolution enhanced black body width of the character, wherein: if it is determined that the character is not a mono-stem character, then the act of adjusting the resolution enhanced black body width of the character comprises multiplying the resolution enhanced black body width of the character by a correction factor defined by the pixel precision advance width of the character divided by the resolution enhanced advance width of the character; and if it is determined that the character is a mono-stem character, then the act of adjusting the resolution enhanced black body width of the character comprises multiplying the resolution enhanced black body width by a correction factor defined by the pixel precision black body width of the character divided by the resolution enhanced black body width of the character; and displaying the document on the display device, wherein the displayed document includes the hinted characters and further has the layout as the layout existed prior to the act of hinting.

Claim 18

In a rendering system that processes characters having existing formatting associated with a pixel precision resolution and renders the characters at a sub-pixel precision resolution, a method for rendering the characters at the sub-pixel precision resolution while maintaining the layout of a document that includes the characters when the characters are rendered at the sub-pixel precision resolution, the method comprising: obtaining a document having a layout associated with pixel precision resolution, the document including characters having a particular font and a particular point size and having pixel precision advance widths and pixel precision black body widths associated with the pixel precision resolution; in preparation for displaying the document on a display device that is capable of displaying the characters with sub-pixel precision resolution, hinting the characters to pixel sub-component boundaries without changing the particular font or the particular point size, thereby: changing the pixel precision black body widths to resolution enhanced black body widths associated with the sub-pixel precision resolution; and changing the pixel precision advance widths to resolution enhanced advance widths associated with the sub-pixel precision resolution; for each of a plurality of the characters in the document, performing the acts of: determining whether the character is a mono-stem character; replacing the advance width of the character with the pixel precision advance width of the character that existed prior to the act of hinting, thereby maintaining the layout of the document as the layout existed prior to the act of hinting; and adjusting the resolution enhanced black body width of the character, wherein: if it is determined that the character is not a mono-stem character, then the act of adjusting the resolution enhanced black body width of the character comprises multiplying the resolution enhanced black body width of the character by a correction factor defined by the pixel precision advance width of the character divided by the resolution enhanced advance width of the character; and if it is determined that the character is a mono-stem character, then the act of adjusting the resolution enhanced black body width of the character comprises multiplying the resolution enhanced black body width by a correction factor defined by the pixel precision black body width of the character divided by the resolution enhanced black body width of the character; and displaying the document on the display device, wherein the displayed document includes the hinted characters and further has the layout as the layout existed prior to the act of hinting.

Claim 19

The method of claim 15 , wherein the act of determining whether the character is a mono-stem character comprises the act of determining whether the pixel precision black body width of the character is no greater than one.

Claim 20

A rendering apparatus for processing characters having existing formatting associated with a pixel precision resolution and rendering the characters at a sub-pixel precision resolution while maintaining the layout of a document that includes the characters when the characters are rendered at the sub-pixel precision resolution, the apparatus comprising: means for obtaining a document having a layout associated with pixel precision resolution, the document including characters having a particular font and a particular point size and having pixel precision advance widths and pixel precision black body widths associated with the pixel precision resolution; means for hinting the characters to pixel sub-component boundaries without changing the particular font or the particular point size in preparation for displaying the document on a display device that is capable of displaying the characters with sub-pixel precision resolution, thereby: changing the pixel precision black body widths to resolution enhanced black body widths associated with the sub-pixel precision resolution; and changing the pixel precision advance widths to resolution enhanced advance widths associated with the sub-pixel precision resolution, at least some of the resolution enhanced advance widths being different from the corresponding pixel precision advance widths; means for replacing said at least some of the resolution enhanced advance widths with the corresponding pixel precision advance widths, thereby maintaining the layout of the document as the layout existed prior to the act of hinting; and means for displaying the document on the display device, wherein the displayed document includes the hinted characters and further has the layout as the layout existed prior to the act of hinting.

Claim 21

A rendering apparatus for processing characters having existing formatting associated with a pixel precision resolution and rendering the characters at a sub-pixel precision resolution while maintaining the layout of a document that includes the characters when the characters are rendered at the sub-pixel precision resolution, the apparatus comprising: means for obtaining a document having a layout associated with pixel precision resolution, the document including characters having a particular font and a particular point size and having pixel precision advance widths and pixel precision black body widths associated with the pixel precision resolution; means for hinting the characters to pixel sub-component boundaries without changing the particular font or the particular point size in preparation for displaying the document on a display device that is capable of displaying the characters with sub-pixel precision resolution, thereby: changing the pixel precision black body widths to resolution enhanced black body widths associated with the sub-pixel precision resolution; and changing the pixel precision advance widths to resolution enhanced advance widths associated with the sub-pixel precision resolution, at least some of the resolution enhanced advance widths being different from the corresponding pixel precision advance widths; means for replacing said at least some of the resolution enhanced advance widths with the corresponding pixel precision advance widths, thereby maintaining the layout of the document as the layout existed prior to the act of hinting; and means for displaying the document on the display device, wherein the displayed document includes the hinted characters and further has the layout as the layout existed prior to the act of hinting.

Claim 22

The apparatus of claim 17 , further comprising means for adjusting the resolution enhanced black body width of each of a plurality of characters based on the resolution enhanced advance width of the character and the pixel precision advance width of the character.

Claim 23

The rendering apparatus of claim 18 , wherein the means for adjusting the resolution enhanced black body width of each of the plurality of characters comprises means for multiplying the resolution enhanced black body width of the character by a correction factor defined by the pixel precision advance width of the character divided by the resolution enhanced advance width of the character, wherein means for limiting the correction factor is limited if the correction factor would otherwise be greater than a predetermined maximum limit.

Claim 24

The apparatus of claim 18 , wherein the means for adjusting the resolution enhanced black body width of each of the plurality of characters comprises means for multiplying the resolution enhanced black body width of the character by a correction factor defined by the pixel precision advance width of the character divided by the resolution enhanced advance width of the character, wherein the correction factor is limited if the correction factor would otherwise be less than a predetermined minimum limit.

Claim 25

The apparatus of claim 18 , further means for moving the black body of a particular character to the left prior to displaying the document if the resolution enhanced black body width of the particular character is greater than the pixel precision black body width of the particular character.

Claim 26

The apparatus of claim 18 , further means for moving the black body of a particular character outline to the right prior to displaying the document if the resolution enhanced black body width of the particular character is less than the pixel precision black body width of the particular character.

Claim 27

A rendering apparatus for processing characters having existing formatting associated with a pixel precision resolution and for rendering the characters at a sub-pixel precision while maintaining the layout of a document that includes the characters when the characters are rendered at the sub-pixel precision resolution, the apparatus comprising: means for obtaining a document having a layout associated with pixel precision resolution, the document including characters having a particular font and a particular point size and having pixel precision advance widths and pixel precision black body widths associated with the pixel precision resolution; means for hinting the characters to pixel sub-component boundaries without changing the particular font or the particular point size in preparation for displaying the document on a display device that is capable of displaying the characters with sub-pixel precision resolution, thereby: changing the pixel precision black body widths to resolution enhanced black body widths associated with the sub-pixel precision resolution; and changing the pixel precision advance widths to resolution enhanced advance widths associated with the sub-pixel precision resolution; means for performing, for each of a plurality of the characters in the document, the functions of: determining whether the character is a mono-stem character; replacing the advance width of the character with the pixel precision advance width of the character that existed prior to hinting, thereby maintaining the layout of the document as the layout existed prior to hinting; and adjusting the resolution enhanced black body width of the character, wherein: if it is determined that the character is not a mono-stem character, then the means for adjusting the resolution enhanced black body width of the character multiplies the resolution enhanced black body width of the character by a correction factor defined by the pixel precision advance width of the character divided by the resolution enhanced advance width of the character; and if it is determined that the character is a mono-stem character, then the means for adjusting the resolution enhanced black body width of the character multiplies the resolution enhanced black body width by a correction factor defined by the pixel precision black body width of the character divided by the resolution enhanced black body width of the character; and means for displaying the document on the display device, wherein the displayed document includes the hinted characters and further has the layout as the layout existed prior to hinting.

Claim 28

A rendering apparatus for processing characters having existing formatting associated with a pixel precision resolution and for rendering the characters at a sub-pixel precision while maintaining the layout of a document that includes the characters when the characters are rendered at the sub-pixel precision resolution, the apparatus comprising: means for obtaining a document having a layout associated with pixel precision resolution, the document including characters having a particular font and a particular point size and having pixel precision advance widths and pixel precision black body widths associated with the pixel precision resolution; means for hinting the characters to pixel sub-component boundaries without changing the particular font or the particular point size in preparation for displaying the document on a display device that is capable of displaying the characters with sub-pixel precision resolution, thereby: changing the pixel precision black body widths to resolution enhanced black body widths associated with the sub-pixel precision resolution; and changing the pixel precision advance widths to resolution enhanced advance widths associated with the sub-pixel precision resolution; means for performing, for each of a plurality of the characters in the document, the functions of: determining whether the character is a mono-stem character; replacing the advance width of the character with the pixel precision advance width of the character that existed prior to hinting, thereby maintaining the layout of the document as the layout existed prior to hinting; and adjusting the resolution enhanced black body width of the character, wherein: if it is determined that the character is not a mono-stem character, then the means for adjusting the resolution enhanced black body width of the character multiplies the resolution enhanced black body width of the character by a correction factor defined by the pixel precision advance width of the character divided by the resolution enhanced advance width of the character; and if it is determined that the character is a mono-stem character, then the means for adjusting the resolution enhanced black body width of the character multiplies the resolution enhanced black body width by a correction factor defined by the pixel precision black body width of the character divided by the resolution enhanced black body width of the character; and means for displaying the document on the display device, wherein the displayed document includes the hinted characters and further has the layout as the layout existed prior to hinting.