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Subject: RE: [sarif] Image files: wait just a minute here!
I don’t know. Jim, is it possible that now that we’ve restricted ourselves to raster-based image formats, that we can restrict the coordinates to non-negative integers? From: Michael Fanning <Michael.Fanning@microsoft.com> Thanks Larry. I am not a raster image format expert. Is there, in fact, a pixel-based image format that supports negative (and/or non-integral) pixel values? “Pixel values MAY be positive of negative, depending on the natural coordinate system of the image” From: Larry Golding (Comcast) <larrygolding@comcast.net> FYI, here’s the relevant text in the provisional draft: 3.14.5 [attachment.]rectangles propertyIf the attachment is a raster-based image file (for example .png, .jpg, .gif, or .bmp), an attachment object MAY contain a property named rectangles whose value is an array of one or more unique (§3.6.2) rectangle objects (§3.23), each of which specifies an area of interest within the image. These rectangle objects SHOULD contain a message property (§3.23.3) so a user can understand their relevance. If the attachment is not a raster-based image file, rectangles SHALL be absent. NOTE: If a SARIF producer wished to highlight areas in a non-raster based image file such as .svg, or a non-image file such as .pdf, it might export the file to a raster-based image format, attach the exported image file, and specify the rectangles on that image. … 3.23.2 [rectangle.]top, left, bottom, and right propertiesA rectangle object SHALL contain properties named top, left, bottom, and right, each of which contains a number (as defined by [JSCHEMA01]) specifying one of the coordinates of the rectangle within the image. These properties SHALL be measured in pixels. Pixel values SHALL increase from left to right and from top to bottom. Pixel values MAY be positive of negative, depending on the natural coordinate system of the image. NOTE: A number in JSON schema can take a variety of forms, including simple integers (42) and floating point numbers (3.14). Larry From: sarif@lists.oasis-open.org <sarif@lists.oasis-open.org> On Behalf Of Larry Golding (Comcast) Thanks Michael. That raises a procedural issue: according to the minutes, the TC approved #137 with certain changes. Most of them are still good, but this part of this one is not: Jim: make values float and change pixels to units appropriate for format I will merge the changes as we’ve discussed here: supporting only raster-based formats and requiring units of pixels (although they are float values, and can be signed). Then I will add an item to the agenda for the next TC meeting to ratify this decision. Larry From: Michael Fanning <Michael.Fanning@microsoft.com> Ok, so we might indeed have really tied ourselves into knots. Your original text, perhaps with the addition of emphasizing that this construct is relevant for raster image formats only, was right (including the use of the term pixels). In hindsight, I personally regret my contributions to this discussion. 😊 From: sarif@lists.oasis-open.org <sarif@lists.oasis-open.org> On Behalf Of Larry Golding (Comcast) We got tied up in knots this morning discussing how to draw rectangles on files like PDF and SVG. But PDF is not an image format. If a SARIF producer wants to draw rectangles on a PDF, it can take a screenshot, or use a PDF-to-JPEG converter. Likewise, SVG (although unquestionably an image format) is a text representation. A SARIF producer could specify a region containing the XML elements of interest, and a viewer that knows how to render SVG could add the necessary decorations to highlight the area. Or again, the producer could convert to a pixel-based image file. We can certainly continue to talk about improvements to image-like attachments, but I propose we limit “rectangle” support to pixel-based image files, and suggest “take a screenshot” or “convert to JPEG or PNG” for anything else. After all, the original motivation for what became generic image support was precisely that: screenshots. Larry |
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