<html><head></head><body style="zoom: 0%;"><div dir="auto">Hi,<br><br></div>
<div dir="auto">I'm finishing png support.<br></div>
<div dir="auto">Thierry<br><br></div>
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<div class="gmail_quote" >Le 17 déc. 2019, à 13:32, Ulf Zibis <<a href="mailto:ulf.zibis@gmx.de" target="_blank">ulf.zibis@gmx.de</a>> a écrit:<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<pre class="blue">Hi Olaf,<br><br>Am 17.12.19 um 12:36 schrieb Olaf Meeuwissen:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #729fcf; padding-left: 1ex;"> Thierry Hucard writes:<br><br><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #ad7fa8; padding-left: 1ex;"> Le 15 déc. 2019 à 19:56, à 19:56, Ulf Zibis <ulf.zibis@gmx.de> a écrit:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #8ae234; padding-left: 1ex;"> Am 15.12.19 um 19:43 schrieb thierry@ordissimo.com:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #fcaf3e; padding-left: 1ex;"> Le 2019-12-15 18:34, Ulf Zibis a écrit:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #e9b96e; padding-left: 1ex;"> Hi List,<br><br> Am 15.12.19 um 09:10 schrieb Olaf Meeuwissen:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #ccc; padding-left: 1ex;"> The backend currently only supports image data transfer in JPEG format<br> but Thierry indicated he wanted to add support for PNG and PDF as well.<br></blockquote> Would it be possible to also support the TIFF format, as for<br> black&white it is the best compressing with Fax G4 compression?<br></blockquote> I didn't see any device managing Tiff, send me the capability file,<br> I could add the support.<br> [...]<br></blockquote> In my understanding, it's not the scanner, which supports the TIFF<br> format, but it has to send raw (or lossless compressed) format, so<br> sane or the sane frontend could compress to TIFF.<br></blockquote> No the backend receives the scanner data (the jpeg format always seems<br> to be present), it can be jpeg, png, pdf or octet-stream. I didn't see<br> any tiff. The data is compressed and sent back to the frontend.<br></blockquote> As Thierry indicated, the JPEG support by the escl backend is a matter<br> of the communication between the device and the backend. For any SANE<br> frontend, that doesn't really matter as the SANE Standard only allows<br> for a "raw" image format. Any backend *has* to convert to SANE's raw<br> image format before handing image data to the frontend.<br><br> Doing device-backend image data transfer using JPEG is lossy in all but<br> the most uncommon scenarios. That is, image quality suffers. If the<br> device-backend image data transfer can use PNG, which is not lossy, that<br> would be a big improvement, image quality-wise.<br><br> BTW, I fear that any PDF device-backend image data transfer is just a<br> JPEG image wrapped in PDF but that remains to be seen.<br> Wishful thinking says PNG-in-PDF is out there somewhere, maybe.<br><br> Hope this helps,<br></blockquote><br>Yes it helps to understand the issue, much thanks.<br><br>If escl becomes common in future, I can imagine, sane additionally could<br>provide a JPEG format interface to benefit from the faster transmission<br>between scanner and backend, especially if the transport is over network<br>and image quality doesn't matter so much.<br><br>-Ulf<br><br><br></pre></blockquote></div></body></html>