[sane-devel] SANE2 standard revisited: Well-Known Options
Fri, 6 Dec 2002 21:45:53 +0100
On Thu, Dec 05, 2002 at 06:09:57PM +0100, Henning Meier-Geinitz wrote:
|4.5.2 Scan Resolution Options
| Option resolution is used to select the resolution at which an image
| should be acquired. When the backend wants to allow different values
| for x- and y-resolution it has to define the options x_resolution and
| y_resolution. Note that only the option resolution or the options
| x_resolution and y_resolution may be active.
"... may be active at the same time" to make it more clear.
The option names are "x-resolution" and "y-resolution", aren't they?
The underscore is not allowed in the name.
| 4.5.4 Scan Area Options
Shouldn't we add the usual standard-disclaimer: "This option is not
mandatory, but if a backend does support it, it must implement it in a
manner consistent with the above definition. "?
|4.5.6 Gamma table options
| The backend should not use the gamma tables to emulate other functions
| or options like highlight, shadow, contrast, brightness, threshold,
But doing a gamma table in software is allowed?
I would move the Gamma table options to the Thershold, Annalog Gamma,
Shadow and Highlight options, that's where it fits better than between
depth and scan mode.
| 4.5.9 Threshold
| The option threshold is used to define the threshold for Lineart and
| maybe Halftone mode. In multi bit modes this option should be set
| inactive. The type of this option is SANE_TYPE_FIXED. The unit is
| SANE_UNIT_PERCENT. The value range should be 0.0...100.0 if possible.
| It defines the minimum intensity to get a white point / full intensity
| (image data bit = 0).
The bit is only 0 in RAW mode for gray frames. For color frames (the
funny 1 bit color mode) it's one. And it may be anything for MIME
types. So i would just remove "(image data bit = 0)", white point/full
intensity is clear enough. Same for the rest of the text.
I'll write about scan buttons in a separate email because that will
become more complex, I guess.
New Well Known Options:
set focus position FOCUS_POS_X, FOCUS_POS_Y
As I don't know what's the idea of that one, the proponent should
(From Oliver Rauch, the text is from me):
"4.5.15 Batch scan options
The batch scan options can be used by a frontend to indicate that more
than one image will be scanned in a batch. The backend provides the
options batch-scan-start, batch-scan-loop, batch-scan-end,
batch-scan-next-tl-x, batch-scan-next-tl-y, batch-scan-next-br-x, and
batch-scan-next-br-y. The first three options are of type
SANE_TYPE_BOOL and indicate that the next scan is the first scan, the
second or following or the last scan of a batch respectively. The
batch-scan-next options specify the coordinates of the next scan and
follow the same rules as the scan area option (see section ...).
These options are not mandatory, but if a backend does support them,
it must implement them in a manner consistent with the above definition.
In this case, all options must be implemented."
Some points of discussion:
- Are all four geometry options necessary? If a device scans from
top-to-bottom, tl-y would be sufficiant. However, there may exist
device with a different scanning direction and the standard say,
it's the job of the backend to transform coordinates. So we can't
just redefine the top-left edge to something else. Do such devices
- Instead of three bool options, one sring-list option would be
possible. This would avoid the case of more than one option is set
by a misdirected frontend. On the other hand, these options should
be handeld by the frontend, not the user so bool is easier to handle.