{"id":820,"date":"2008-12-15T00:18:11","date_gmt":"2008-12-15T04:18:11","guid":{"rendered":"http:\/\/www.ezrasf.com\/wplog\/?p=820"},"modified":"2008-12-16T22:15:30","modified_gmt":"2008-12-17T02:15:30","slug":"division-issue-in-yapb","status":"publish","type":"post","link":"https:\/\/www.ezrasf.com\/wplog\/2008\/12\/15\/division-issue-in-yapb\/","title":{"rendered":"Division Issue in YAPB"},"content":{"rendered":"

Problem PHP in Yet Another Photoblog causes “Warning<\/strong>: Division by zero in\u00c2\u00a0exifReader.inc\u00c2\u00a0<\/strong>on line\u00c2\u00a0859” (the problem line is in bold):<\/span><\/strong><\/p>\n

\u00c2\u00a0<\/p>\n

case TAG_SHUTTERSPEED:
\n\u00c2\u00a0\u00c2\u00a0\/\/ More complicated way of expressing exposure time, so only use
\n\u00c2\u00a0\u00c2\u00a0\/\/ this value if we don’t already have it from somewhere else.
\n\u00c2\u00a0\u00c2\u00a0if ($this->ImageInfo[TAG_EXPOSURETIME] == 0){
\n\u00c2\u00a0\u00c2\u00a0 \u00c2\u00a0$sp = $this->ConvertAnyFormat($ValuePtr, $Format);
\n\u00c2\u00a0\u00c2\u00a0 \u00c2\u00a0\/\/ Temporary Workaround for divizion by zero problem
\n\u00c2\u00a0\u00c2\u00a0 \u00c2\u00a0 \u00c2\u00a0if (!empty($sp[0])) {
\n\u00c2\u00a0\u00c2\u00a0 \u00c2\u00a0 \u00c2\u00a0 \u00c2\u00a0$this->ImageInfo[TAG_SHUTTERSPEED] = (1\/exp($sp[0]*log(2)));<\/strong>
\n\u00c2\u00a0\u00c2\u00a0 \u00c2\u00a0 \u00c2\u00a0} else {
\n\u00c2\u00a0\u00c2\u00a0 \u00c2\u00a0 \u00c2\u00a0 \u00c2\u00a0$this->ImageInfo[TAG_SHUTTERSPEED] = 0;
\n\u00c2\u00a0\u00c2\u00a0 \u00c2\u00a0 \u00c2\u00a0}
\n\u00c2\u00a0\u00c2\u00a0 \u00c2\u00a0}
\n\u00c2\u00a0\u00c2\u00a0 \u00c2\u00a0break;<\/p><\/blockquote>\n

\u00c2\u00a0<\/p>\n

Looks like YAPB is attempting to create a value if one doesn’t exist for\u00c2\u00a0TAG_EXPOSURETIME by inventing a new value. In my problem picture, the exposure time is\u00c2\u00a00.003 seconds which != 0. So why is the\u00c2\u00a0($this->ImageInfo[TAG_EXPOSURETIME] == 0)\u00c2\u00a0condition evaluated as true?\u00c2\u00a0<\/p>\n

Interestingly, just prior to this is some code dealing with TAG_EXPOSURETIME which seems to be affecting this. Changing the 0.5 to 0.0005 (less than my current value removes the problem.<\/p>\n

case TAG_EXPOSURETIME:
\n\u00c2\u00a0\u00c2\u00a0\/\/ Simplest way of expressing exposure time, so I trust it most.
\n\u00c2\u00a0\u00c2\u00a0\/\/ (overwrite previously computd value if there is one)
\n\u00c2\u00a0\u00c2\u00a0$tmp = $this->ConvertAnyFormat($ValuePtr, $Format);
\n\u00c2\u00a0\u00c2\u00a0$this->ImageInfo[‘h’][“exposureTime”] = sprintf(“%6.4f s (%d\/%d)”,(double)$tmp[0],$tmp[1][0],$tmp[1][1]);
\n\u00c2\u00a0\u00c2\u00a0if ($tmp[0] <= 0.5){
\n\u00c2\u00a0\u00c2\u00a0 \u00c2\u00a0$this->ImageInfo[‘h’][“exposureTime”] .= sprintf(” (1\/%d)”,(int)(0.5 + 1\/$tmp[0]));
\n\u00c2\u00a0\u00c2\u00a0}<\/strong>
\n\u00c2\u00a0\u00c2\u00a0break;<\/p><\/blockquote>\n

With this conditional, the exposure time is “0.003 s\u00c2\u00a0(1\/400)\u00c2\u00a0(1\/400)” without “0.003 s (1\/400)”. Didn’t see a reason to have it twice, so I’ve dropped it.<\/p>\n

Also, I figure it would be better to call\u00c2\u00a0ImageInfo[‘h’][“exposureTime”] instead of\u00c2\u00a0ImageInfo[TAG_EXPOSURETIME]. With this change, it seems to have resolved the issue for me.<\/p>\n","protected":false},"excerpt":{"rendered":"

Problem PHP in Yet Another Photoblog causes “Warning: Division by zero in\u00c2\u00a0exifReader.inc\u00c2\u00a0on line\u00c2\u00a0859” (the problem line is in bold): \u00c2\u00a0 case TAG_SHUTTERSPEED: \u00c2\u00a0\u00c2\u00a0\/\/ More complicated way of expressing exposure time, so only use \u00c2\u00a0\u00c2\u00a0\/\/ this value if we don’t already have it from somewhere else. \u00c2\u00a0\u00c2\u00a0if ($this->ImageInfo[TAG_EXPOSURETIME] == 0){ \u00c2\u00a0\u00c2\u00a0 \u00c2\u00a0$sp = $this->ConvertAnyFormat($ValuePtr, $Format); \u00c2\u00a0\u00c2\u00a0 […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"activitypub_content_warning":"","activitypub_content_visibility":"","activitypub_max_image_attachments":4,"activitypub_interaction_policy_quote":"anyone","activitypub_status":"","footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[165],"tags":[457,651,458,460,456,993,459,294,404,461],"class_list":["post-820","post","type-post","status-publish","format-standard","hentry","category-wordpress","tag-condition","tag-exif","tag-exposure-time","tag-photoblog","tag-php","tag-rar-archive","tag-shutter-speed","tag-trust","tag-workaround","tag-yapb"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p1rUBW-de","jetpack-related-posts":[],"jetpack_likes_enabled":true,"_links":{"self":[{"href":"https:\/\/www.ezrasf.com\/wplog\/wp-json\/wp\/v2\/posts\/820","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ezrasf.com\/wplog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ezrasf.com\/wplog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ezrasf.com\/wplog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ezrasf.com\/wplog\/wp-json\/wp\/v2\/comments?post=820"}],"version-history":[{"count":0,"href":"https:\/\/www.ezrasf.com\/wplog\/wp-json\/wp\/v2\/posts\/820\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.ezrasf.com\/wplog\/wp-json\/wp\/v2\/media?parent=820"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ezrasf.com\/wplog\/wp-json\/wp\/v2\/categories?post=820"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ezrasf.com\/wplog\/wp-json\/wp\/v2\/tags?post=820"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}