Pixel blur on stroked lines

Hi Tim,

You get the blurred lines because they are not positioned exactly on the pixel grid.

When an 1 pixel wide line (or in InDesign 1 pt, which is the same) falls between pixels, it is anti-aliased when converted to a bitmap and shades of grey are introduced. Anti-aliasing is nice for type and curves, but not for horizontal or vertical lines. If the line is positioned exactly on the pixel grid, it would be a sharp 1 pixel wide line.

What you would like to have in InDesign to avoid this is an "Align and Snap to Pixel Grid" like Illustrator has.

You can request this here:

https://www.adobe.com/cfusion/mmform/index.cfm?name=wishform

In the mean time, try this for new documents designed for tablets:

Create a new document with the pixel dimensions of your tablet.

Go to the preferences and select Grids

For Document Grid, enter the same amount for horizontal, vertical and subdivisions. I put 100 in all of these boxes.

This creates a one pixelwide pixel grid.

In InDesign go to the View menu and select Grids & Guides: Show Document Grid (you can turn that off later) and Snap to Document Grid.

This will cause your lines to snap to the grid, but they will not be positioned on the pixel, but between the pixels because by default the stroke is aligned to the center of the lines. They do snap to the grid lines and will cover half a pixel on each side of the line. This will give you blurred ant-aliased lines.

To avoid this, make sure you do not have anything selected and go to Window/Stroke.

Click on the Align Stroke / Align Stroke to Inside icon (or Outside if you prefer).

This will cause all the lines and boxes to fall exactly on the pixel grid.

Save the document as an InDesign template and use this in the future to avoid the blurred lines.

On the far left lines that fall exactly on the pixel grid and next to them lines that fall between pixels. On the right the resulting bitmaps.

regards,

Ton

Anything in a scrollable frame is rasterized and likely to have lower quality than static objects.

Bob

It’s especially noticeable with PDF format folios. All I can tell you is to experiment with different fonts and stay away from those with very thin serifs as these seem to look worse. Also very thin fonts will look pretty bad, too, in comparison to those that haven’t been rasterized. One idea is to use PNG on those pages to rasterize everything so that the fonts at least look the same.

Bob

@Tim – what kind of folios do you create? PDF ones?
Then the static part is no problem at all concerning text representation.

Scrollable frames however could become a little blurry if you zoom in.
They, together with overlay types like "Buttons", "Slideshows" and "Audio Skins" are resampled.

And the resolution of the resampling process depends  on the folio size:

1024 x 768 pdf-folios on an iPad3
or

2048 x 1536 pdf-folios on an iPad3

Uwe