I have a picture that I'd like to include in the center of the page. I don't want the picture to scale. So I tried this (among a lot of other variations):
\begin{figure}[htb]
\centering
\includegraphics{overview_pyramid.png}
\caption{Overview pyramid}\label{fg:overview_pyramid}
\end{figure}
Why isn't this working? I center the image and I don't set a specific size. Nevertheless the picture is scaled (but don't know the factor) and is on the left end of the page.
Your PNG probably doesn't have the correct resolution information set in its metadata. If you have ImageMagick on your system, you can run identify -verbose overview_pyramid.png to see the metadata of the image. If the output contains Units: Undefined and/or a Resolution: that is incorrect, you need to add the information.
You can do this using the command convert overview_pyramids.png -density 300 -units PixelsPerCentimeter overview_pyramids.png to set the resolution to 300 pixels per centimetre, for instance; or just convert overview_pyramids.png -units PixelsPerInch overview_pyramids.png if the value of the "Density" field is correct but the unit is missing.
-verbose switch to get the information on the resolution and the physical size (called Print size in ImageMagick)
– Jake
Feb 6 '11 at 15:41
\textwidth, which would lead to the caption being correctly centered with regard to the text, but the figure being aligned with the left text margin and spilling into the right margin. To resolve this, you can follow what Stefan Kottwitz suggests in his blog: Enclose the figure with \makebox: \makebox[\textwidth]{\includegraphics{overview_pyramid.png}}. This also eliminates the need for the \centering command in your figure.
– Jake
Feb 7 '11 at 20:33
exif:XResolution: 3500000/10000 instead of exif:XResolution: 350/1 — Same resolution, just expressed differently, causing all kinds of image problems. Nothing looked wrong in Photoshop. But identify -verbose my_image.jpg | grep "Resolution" revealed the truth.
– Leif
Sep 25 '15 at 18:01
Images are not scaled, if you don't set any scaling options.
Bitmap images like PNG and JPEG, have a "natural" pixel density. This is often 72DPI or 96DPI, but can be changed by softwares. On the other hand, PDF readers has its own video pixel density, it may be 96DPI, 110DPI or any other value you set. If the density of image and the PDF reader match, and in PDF reader you set the 100% scaling, you'll find the image looks unscaled.
\labelalways come AFTER\caption(or other to-be-labeled elements like\section, etc.). The caption increments the figure or table number to which the label refers. Using\labelbefore\captionlabels the previous figure or table (correct: the last\captionin the same float type). – Martin Scharrer♦ Feb 6 '11 at 15:05centerenvironment -- it adds unwanted margins. Simply use the\centeringmacro after\begin{figure}. – Martin Scharrer♦ Feb 6 '11 at 15:07