I've been struggling with this for a while, and now that I've finally achieved success, I wanted to report my results for anyone else to benefit from.
My mission was to get my PowerBook to drive my Sharp LC-37GD4U at its native resolution. There were three points to this objective: 1) Use the entire screen, 2) Have an unscaled (i.e. "perfect") image, and 3) have the entire image fit on the screen (i.e. no overscan).
The trouble comes from the fact that the native resolution of the panel is 1366x768, but that resolution is not presented as an option by OS X. An interesting side note is that you can connect your DVI output to the DVI input and also with the right cable, the HDMi input. The HDMI input allows a resolution of 1344x756 - very close to native, but no way to fine tune it. The HDMI image will be overscanned - too big for the screen by about an inch all the way around - and it will be scaled, so lots of images will look worse on it than they do on a computer display. The Sharp offers excellent fine tuning capabilities on the DVI input, but absolutely none on the HDMI input.
The DVI input offers 1280x768 - also very close to native, but far enough that it gets scaled. However,
along the way I realized that if I set the view mode to "dot by dot" (instead of sidebar, zoom or stretch) - that it does not get scaled, and that with some fine tuning
, you can align the signal with the panel for a perfect image. More on that below. But the point is I could have stopped here, having achieved a perfect image and use of 100% of the panel's vertical resolution, and 94% of it's horizontal resolution.
So keep in mind, if you continue here, all you are going to get, beyond going with 1280x768, dot by dot, and fine-tuning, is 86 more pixels. It is worth noting that with the same utility that I used, you could theoretically customize 1344x756 over the HDMI to fit in the screen (not be overscanned), but I didn't put much time into this.
Anyway, the way I got the full resolution was with a utility called SwitchRes X
. This allows you to define custom resolution settings beyond those that OS X by default is willing to display, which many moderm Mac video cards will allow. Custom resolutions are quite complicated, with many parameters who's names or implications make little sense to me. Windows users have a utility called PowerStrip which serves the same purpose. It took a while to figure out how to come up with settings that had any chance of being valid. I've written a little SRX Helper-FAQ
that explains what little I do know about making valid settings.
As for drving my Sharp LCD at it's native resolution, Here is what works. I would expect this to work equally for the LC-37GD6U, LC-37G4U, and possibly all Sharp LCD's who's native resolution is 1366x768. In particular, these values are probably specific to the Radeon 9200 that is build into my PowerBook, or possibly several of the Radeon series video cars. Note: Don't bother installing ATI's custom drivers. I did, and they didn't provide or enable any different capability.
Pixel Clock*: 74.25 MHz
Value Horizontal Vertical
Active 1360 768
Front Porch 130 0
Sync Width 114 0
Back Porch 40 0
Scan Rate* 45 kHz 58.593 Hz
* Pixel Clock and Scan Rate are intrinsically tied together and are a function of each other and the other values. My FAQ linked above explains as much as I understand about this. Simply put, you do not enter the Scan Rate values (even though the fields are editable). Rather, You enter Pixel Clock first, then all the other values - and both scan rates will be calculated for you.
Note that I'm sacrificing 6 pixels in horizontal resolution - this is the best I could get the OS and video card driver to accept (in other words, it's the closest value set I tried in SRX that actually showed up as selectable). For 6 pixels I was willing to declare victory.
Before you fine tune your TV, do the following on:
Select the DVI input (if you haven't already)
Menu->Setup->Input: Set it to 1366x768
View Mode: Select "dot by dot".
As I mentioned above, once you have the proper resolution, you have to calibrate your display to optimize its appearance. Initially it will probably be scaled slightly and flickering a little. The scaling will make certain types of imagery appear to have bands of varying color, where there should be a consistent color or pattern. If you tell your Sharp to Auto-Sync (Menu->Setup), and you've done the above settings first, it will probably get the resolution alignd correctly, but leave you with some flickering. I wrote up a detailed fine tuning
post on the procedure I used to manually align the resolution, and remove the flickering. The test image I used for this procedure is attached.