Guidelines - Revision history

Arnaud Cheritat: /* Antialias */

2014-12-10T16:50:06Z

‎Antialias

Arnaud Cheritat: /* Antialias */

2014-12-10T15:47:48Z

‎Antialias

Arnaud Cheritat: /* Antialias */

2014-12-10T15:42:14Z

‎Antialias

Arnaud Cheritat at 15:39, 10 December 2014

2014-12-10T15:39:20Z

Arnaud Cheritat: /* Antialias */

2014-12-10T15:32:22Z

‎Antialias

Arnaud Cheritat: /* Antialias */

2014-12-10T15:30:09Z

‎Antialias

Arnaud Cheritat: /* Antialias */

2014-12-10T15:27:06Z

‎Antialias

Arnaud Cheritat: /* Antialias */

2014-12-10T15:26:41Z

‎Antialias

Arnaud Cheritat: /* Bitmaps */

2014-12-10T14:47:03Z

‎Bitmaps

Arnaud Cheritat: /* File format */

2014-12-10T14:46:26Z

‎File format

@@ Line 43: / Line 43: @@
 [[Image:L1b.png]][[Image:L3b.png]][[Image:L2b.png]]
 Below, the same three images, shown at normal scale:
 [[Image:L1.png]][[Image:L3.png]][[Image:L2.png]]
 On a typical screen in 2014 the image on the right looks smoother that the other two images.
@@ Line 54: / Line 56: @@
 There is a specific phenomenon, [[moire|moiré]] that we will illustrate on particular examples that the author of the pages you are reading actually encountered while producing mathematical illustrations.

@@ Line 40: / Line 40: @@
 Caution: in some image manipulation programs, you need to convert paletted images to true color before downscaling, or the program may, instead of averaging the color, use the nearest matching color in the palette, resulting in the absence of antialias.
-For instance, the following image (left) shows a thick line. All pixels are black or white. It has been downscaled by a factor of two in two ways: by color of nearest pixel (middle image), by averaging grayscale value on 4 pixels (right).
+For instance, the following image (left) shows a thick line. All pixels are black or white. It has been downscaled by a factor of two in two ways: by color of nearest pixel (middle image), by averaging grayscale value on 4 pixels (right). The image on the right is considered as an antialiased version of the image in the middle: note that to produce it, one needs to compute 4 times more pixels than for the middle image, because one must first compute the image on the left.
 [[Image:L1b.png]][[Image:L3b.png]][[Image:L2b.png]]

@@ Line 36: / Line 36: @@
 (This concerns bitmap graphics only.)
-Even if you plan to include to produce a small image or include it in a web browser, thus need only low [[resolution]], I recommend to produce a higher resolution picture first, and then [[downscale]] it. This is the principle of [http://en.wikipedia.org/wiki/Antialias antialias]. A double resolution 2W×2H -> W×H already gives a very good improvement. I recommend using integer multiples 2W, 3W, etc... Note that for images with uniform color areas, the downscaled PNG will have a size comparable to the original, possibly bigger.
+Even if you plan to include to produce a small image or include it in a web browser, thus need only low [[resolution]], I recommend to produce a higher resolution picture first, and then [[downscale]] it. This is the principle of [http://en.wikipedia.org/wiki/Antialias antialias]. A double resolution 2W×2H -> W×H already gives a very good improvement. I recommend using integer multiples 2W, 3W, etc... Higher multiples can be useful to fight against [[moire|moirés]]. Note that for images with uniform color areas, the downscaled PNG will have a size comparable to the original, possibly bigger.
 Caution: in some image manipulation programs, you need to convert paletted images to true color before downscaling, or the program may, instead of averaging the color, use the nearest matching color in the palette, resulting in the absence of antialias.
@@ Line 53: / Line 53: @@
 There has been some screens with very high spatial resolution around for some time (the Apple company calls them Retina screens), I do not how these images render on them.
-PARLER : des moirés.
+There is a specific phenomenon, [[moire|moiré]] that we will illustrate on particular examples that the author of the pages you are reading actually encountered while producing mathematical illustrations.

@@ Line 40: / Line 40: @@
 Caution: in some image manipulation programs, you need to convert paletted images to true color before downscaling, or the program may, instead of averaging the color, use the nearest matching color in the palette, resulting in the absence of antialias.
-For instance, the following image (left) shows a thick line. All pixels are black or white. It has been downscaled by a factor of two in two ways: by color of nearest pixel (middle image), by averaging grayscale value on 4 pixels (middle image).
+For instance, the following image (left) shows a thick line. All pixels are black or white. It has been downscaled by a factor of two in two ways: by color of nearest pixel (middle image), by averaging grayscale value on 4 pixels (right).
 [[Image:L1b.png]][[Image:L3b.png]][[Image:L2b.png]]
-In Gimp, the averaging scale method is called "Linear" in the "scale image" menu (2014).
+In [[http://www.gimp.org| Gimp]] and in many other programs, the scaling method by averaging is called "Linear" (2014).
 Below, the same three images, shown at normal scale:
@@ Line 52: / Line 52: @@
 On a typical screen in 2014 the image on the right looks smoother that the other two images.
 There has been some screens with very high spatial resolution around for some time (the Apple company calls them Retina screens), I do not how these images render on them.

@@ Line 44: / Line 44: @@
 [[Image:L1b.png]][[Image:L3b.png]][[Image:L2b.png]]
-The same three images, shown at normal scale:
+In Gimp, the averaging scale method is called "Linear" in the "scale image" menu (2014).
 [[Image:L1.png]][[Image:L3.png]][[Image:L2.png]]
 On a typical screen in 2014 the image on the right looks smoother that the other two images.
 There has been some screens with very high spatial resolution around for some time (the Apple company calls them Retina screens), I do not how these images render on them.

@@ Line 45: / Line 45: @@
 The same three images, shown at normal scale:
-[[Image:L1.png][[Image:L3.png]][[Image:L2.png]]
+[[Image:L1.png]][[Image:L3.png]][[Image:L2.png]]
 On a 2014 screen, the image on the right looks smoother that the other two images.

← Older revision		Revision as of 15:26, 10 December 2014
Line 39:		Line 39:

	Caution: in some image manipulation programs, you need to convert paletted images to true color before downscaling, or the program may, instead of averaging the color, use the nearest matching color in the palette, resulting in the absence of antialias.		Caution: in some image manipulation programs, you need to convert paletted images to true color before downscaling, or the program may, instead of averaging the color, use the nearest matching color in the palette, resulting in the absence of antialias.
		+
		+	For instance, the following image (left) shows a thick line. All pixels are black or white. It has been downscaled by a factor of two in two ways: by color of nearest pixel (middle image), by averaging grayscale value on 4 pixels (middle image).
		+
		+	[[Image:L1b.png]][[Image:L3b.png]][[Image:L2b.png]]
		+
		+	The same three images, shown at normal scale:
		+	[[Image:L1.png][[Image:L3.png]][[Image:L2.png]]
		+	On a 2014 screen, the image on the right looks smoother that the other two images.

@@ Line 15: / Line 15: @@
 It has been my favorite for nearly 20 years.
 Back then, to include them in a TeX/LaTeX article there was a tedious conversion to be made from PNG to EPS but now it is recognized by default by pdfLaTeX.
-Of course I don't know what will be the situation in 20 years (anyway, will this wiki still exist?)
+Of course I do not know what will be the situation in 20 years (anyway, will this wiki still exist?)
 Pros for PNG:

@@ Line 8: / Line 8: @@
 </gallery>
-For simple objects, a vector graphics will take much less memory and will look perfect at any scale, while a bitmap's [[resolution]] (number of pixels) needs to be adapted to the situation. A bitmap is more adapted to complex images, like fractals or with elaborated coloring schemes.
+For simple objects, a vector graphics will take much less memory and will look perfect at any scale, while a bitmap's [[resolution]] (number of pixels) needs to be adapted to the situation. A bitmap is more adapted to complex images, like fractals or to elaborated coloring schemes.
 === Bitmaps ===